National Lampoon’s Christmas Vacation is the third installment in the National Lampoon’s Vacation film series, written by 80s filmmaking legend John Hughes and starring Chevy Chase, Beverly D’Angelo and Randy Quaid.

We’ve already laid out our reasoning for why the festive farce should be considered the greatest Christmas movie of all time, and now we’re taking a look under the bonnet to reveal some incredible facts about the Yuletide classic.

30. It’s based on a National Lampoon short story

Third in the National Lampoon Vacation series, the 1989 film is based on the comedy tale Christmas ‘59, which was written by John Hughes nine years earlier. Written for the magazine National Lampoon, this was a sequel to another well-known piece: Vacation ‘58, which had itself been the basis for National Lampoon’s Vacation.

After writing the 1983 original and co-writing 1985’s European Vacation, Christmas Vacation the final movie in the franchise penned by Hughes. The film’s unsuccessful made-for-television sequel was written instead by Matty Simmons, the producer for the first two films.

29. It had a huge budget for a Christmas film

Christmas Vacation had a budget of $28 million, which may not seem much by today’s superhero-shellacking, CGI-flaunting standards. But for its time, this was an incredibly high budget, especially when you consider that it was a comedy without any special effects. To put this into perspective, Ghostbusters – a true pioneer in the field of special effects – was made for roughly the same amount in 1984.

The set did present some costly challenges. One electrician has calculated that it would cost about $16,000 to run the Griswolds’ Christmas lights for 30 days. Ultimately the expense was clearly worth it, as the film grossed $71 million at the US box office. In its opening weekend, this Christmas movie was #2 at the box office, pipped to the post by Back to the Future Part II.

28. Original director Chris Columbus quit because of Chevy Chase’s rudeness

Chris Columbus was originally set to direct Christmas Vacation, but a personality clash between the future Harry Potter director and Chevy Chase threw a spanner in the works. Speaking to the Chicago Magazine in 2015, Columbus said he was initially delighted to be recruited for the movie, but on his first meeting with Chase, his leading man “treated me like dirt.”

Columbus tried to stick out, but when Chase’s behaviour failed to improve, he quit. Luckily for Columbus, his newfound availability left him free to shoot another Christmas film written by Hughes, Home Alone, which proved to be a career-changing blockbuster.

27. The new director hadn’t seen either of the previous films

Replacement director Jeremiah Chechik hadn’t seen either the original Vacation or first sequel European Vacation before agreeing to take the reins on this one. Chechik saw this as a positive, however, as he could enter the project with a clear mind and festive spirit.

In a 2011 interview with Den of Geek, Chechik admitted, “I was nervous about accepting it, because I didn’t know about Chevy and I wasn’t sure if it was too commercial. But I agreed to do it and I had just a fantastic time doing it.” Chechik cited Preston Sturges, Billy Wilder and Howard Hawks as his comedy inspirations while making the movie.

26. Audrey and Rusty swap ages from the previous film

In both National Lampoon’s Vacation and National Lampoon’s European Vacation, Rusty is the older of the two Griswold children. But, rather bizarrely, in this film he somehow becomes Audrey’s younger brother. As Audrey, Juliette Lewis was following in the footsteps of Vacation’s Dana Barron and European Vacation’s Dana Hill.

Swapping around the children and the actors playing them from film to film became something of a joke within the franchise. In his Time Magazine interview, Chevy Chase said it was his idea to replace and change the children so often. “I always wanted to make the joke, “Geez, I hardly ever get the chance to see the kids anymore. I hardly know who they are. We should go on a vacation.'”

25. Johnny Galecki appear in another 1989 Christmas movie, Prancer

Unusually, National Lampoon’s Christmas Vacation was one of only two Christmas themed films to be released in 1989. The other film was Prancer, an American-Canadian fantasy-drama about a girl who befriends one of Santa’s reindeer. Funnily enough, these two Christmas treats have one actor in common: Johnny Galecki.

Of course, Galecki (best known today as Leonard Hofstadter in The Big Bang Theory) also plays Rusty Griswold in Christmas Vacation, following on from actors Anthony Michael Hall and Jason Lively. In Prancer, meanwhile, he plays a character named Billy Quinn.

24. It became the highest-grossing film in the franchise

On its US theatrical release, National Lampoon’s Christmas Vacation ended up becoming the best performing movie of the franchise up to that point. Years later it was dethroned by 2015’s soft reboot/’legacyquel’ Vacation, which made $104 million from a $31 million budget despite its dire reputation among critics.

Like 1997’s fourth instalment Vegas Vacation, 2015’s Vacation (centred on a grown-up Rusty played by Ed Helms) doesn’t carry the old National Lampoon label. However, literally dozens of films have been released with ‘National Lampoon’ as part of the title, though the same creative team was not involved in all of them.

23. Randy Quaid’s Cousin Eddie got his own spin-off movie in 2003

National Lampoon’s Christmas Vacation is the only sequel in the National Lampoon’s Vacation series to have spawned its own sequel in the form of 2003 TV movie National Lampoon’s Christmas Vacation 2: Cousin Eddie’s Island Adventure. This movie is about the adventures of Cousin Eddie and Catherine, once again played by Randy Quaid and Miriam Flynn.

The film follows their misadventures with their children on an island in the South Pacific. Among the stars to feature in the movie were Eric Idle, Beverly Garland and Playboy model and actress Sung Hi Lee. This low-budget affair fared poorly with critics, and it has a 12% approval rating on Rotten Tomatoes.

22. There’s an entire website dedicated to Christmas Vacation merch

The website National Lampoon’s Christmas Vacation Collectibles is dedicated to selling a bizarre array of related merchandise. You can purchase their 8oz glass moose mugs to decorate the Christmas dinner table, not to mention National Lampoon advent calendars. Their miniature items include models of the Griswolds’ house, their garage, Eddie’s RV and the local Jelly of the Month club.

The website’s best-selling item, however, is a model of Cousin Eddie’s Rottweiler named Snots, who is chasing after a squirrel in the snow. Elsewhere on the internet, superfans can purchase themed cushions, leggings and portraits of Eddie attending his RV sewage tank.

21. Chevy Chase broke a finger while punching plastic Santa

In perhaps one of his most relatable moments, Clark Griswold loses patience with the faulty Christmas lights adorning his house. But rather than restarting, Clark takes out his fury on the nearest decorations: the plastic Santa, sleigh and reindeer propped up in the dark on his front lawn.

While filming the scene, Chase punched the Santa ornament so violently that he ended up breaking his pinky finger. Fighting through the pain, Chase didn’t stop filming, and he proceeded to drop-kick Father Christmas into the distance. The producers decided to use this cut in the final movie, along with Chase’s real yells of pain and annoyance.

20. An earthquake occurred during filming

A slight tremor shakes the scene just as the film’s climax, on Christmas Eve, starts to kick off. The crew were busy filming the extended family’s arrival at the Griswold house when a minor earthquake struck, and as surprising as this might be, footage of the natural disaster wound up in the final film.

Watch closely, and you may notice there’s a slight shaking of the camera at the moment where Bethany steps across the threshold – which was reportedly caused by the earthquake itself.

19. The cast reassembled in 2012 for a series of commercials

In 2012, the Christmas Vacation team met once again at the Warner Ranch to film a series of adverts for the US clothing company Old Navy. Chevy Chase, Beverly D’Angelo and Juliette Lewis all made an appearance, along with some of their co-stars from earlier films in the franchise including Anthony Michael Hall, Dana Barron and Jason Lively.

Reprising his role of Clark Griswold, Chase fires up the family home’s Christmas lights once more. In another skit, Clark lovingly chats to his children from the different films in the same living room, addressing Lively as “Euro Rusty.”

18. It was the final film of Mae Questel, best known as the voice of Betty Boop

The actress Mae Questel’s on-screen movie roles are few and far between, but she has an incredibly famous voice. On top of providing the voice of Betty Boop in over 150 animated shorts, Questel also voiced Olive Oyl in Popeye and Casper in the TV cartoon series Casper, the Friendly Ghost.

Having worked in show business since 1930, Questel’s final film performance was in National Lampoon’s Christmas Vacation. She starred as Aunt Bethany, wife to Uncle Lewis, played by Prizzi’s Honor star William Hickey (although in reality the two actors were 19 years apart in age).

17. The cast decorated themselves with adjectives to help Chase remember his Mr Shirley rant

Clark Griswold’s infamous tirade against his boss amid the Christmas festivities draws an audience of shocked family members. But as the actors gathered to face Chase during this scene, the crew worked out a cunning trick to help the star complete his rant with ease. Since the family’s backs are turned to the camera as Chase addresses them, the actors facing Chase each had cue cards strung around their necks.

These cards helped Chase to reel off the full 30 insults that he uses to describe his heartless superior. In an interview with The Dinner Party in 2015, actress Beverly D’Angelo said, “If you watch it you can see him [reading]. His eyes go from character to character as he’s going on in the speech because we’ve got the lines there.”

16. The assistant director was the grandson of It’s a Wonderful Life’s Frank Capra

Christmas Vacation is scattered with references to It’s a Wonderful Life, probably the best-loved Christmas movie of all time. When the Griswolds’ relatives arrive in this movie, It’s a Wonderful Life is playing on the family’s TV set in the background. What’s more, Clark Griswold chops the home’s newel post down with a chainsaw, this is an homage to George Bailey (James Stewart), who is annoyed by a loose newel post in his own house.

There’s another, more personal connection between the 1946 and 1989 festive favourites. It’s a Wonderful Life was directed by Frank Capra, whose children followed him into the business. The legendary director’s grandson Frank Capra III was recruited as the assistant director for Christmas Vacation.

15. National Lampoon’s Vacation’s Brian Doyle-Murray re-appears as a totally different character

Brian Doyle-Murray appears in two of the Vacation movies: National Lampoon’s Christmas Vacation as well as the first film, National Lampoon’s Vacation. In Christmas Vacation, he stars as Clark Griswold’s loathed boss, whose stinginess causes even a SWAT team to shake their heads in disapproval. Previously, in National Lampoon’s Vacation, Doyle-Murray played a clerk working at Kamp Komfort. He refuses to give Clark cash when his credit card is declined.

Just like Chevy Chase, Doyle-Murray made his name on Saturday Night Live, although he joined the team a few years after Chase had left. The Vacation films weren’t Doyle-Murray’s first opportunity to work with Chase. The pair had previously appeared together in 1981 film Modern Problems, and later Doyle-Murray also worked on Chase’s short-lived late-night talk show, The Chevy Chase Show, in 1993.

14. No part of the film takes place on Christmas Day

Given the title, you might assume that National Lampoon’s Christmas Vacation would be at least in part set on Christmas Day. This isn’t actually the case, however: the film only shows the Griswolds’ antics in the days leading up to 25th December, and the story reaches its conclusion on Christmas Eve. Despite this, the film has long since become a popular choice for viewing on Christmas Day itself.

Ellen Latzen, the actress who played Cousin Eddie’s daughter Ruby Sue, has said strangers still recognise her from the timeless Christmas movie. In a 2015 interview with Huffington Post, Latzen said, “I get such amazing compliments and words of thanks and appreciation from so many people that I meet across the board. The thing I get the most is, ‘Oh my God! My family watches it every year, and thanks for being a part of that,’ and that’s so touching to me.”

13. Randy Quaid based Cousin Eddie on someone he knew

Cousin Eddie and his family arrive for the holidays uninvited, parking their RV right at the Griswolds’ doorstep, much to Clark’s dismay. The larger-than-life Eddie was actually based on a real man who Randy Quaid knew in high school. Apparently, Quaid copied mannerisms and expressions from this acquaintance to develop the character of the Griswolds’ quirky relative.

He even returned to the script to write in the memorable tongue-clicks that punctuate Cousin Eddie’s lines. At the time Quaid was at the height of his 80s fame, and he had already starred in 18 movies and shows before accepting the part of Cousin Eddie. This role was a stark contrast to his previous film, Inside the Third Reich, where he played Ernst Hanfstaengl, the real-life friend of Hitler.

12. Jeremiah Chechik directed the film after getting the approval of Stanley Kubrick

Credit: Mark Mainz/Getty Images for DGA/Warner Bros

National Lampoon’s Christmas Vacation was a massive success for first-time director Jeremiah Chechik. Originally a fashion photographer for Vogue then a director of TV commercials, his move to directing comedies may well seem surprising. Speaking to Den of Geek in 2011, he recalled that his early commercials were “gained the notice of [Stanley] Kubrick, who had mentioned them as his favourite American filmmaking.”

This approval from the esteemed auteur director Kubrick built a huge buzz around the hot new director, and he soon landed the Christmas Vacation gig. Chechik went on to direct Benny & Joon and Diabolique, but his career was derailed by critically reviled 1998 flop The Avengers (based on the British 60s TV series, not the Marvel comic book heroes).

11. The girl who played Ruby Sue wore a wig to cover her mullet

Aged only nine, Ellen Latzen was thrilled to be cast in Christmas Vacation in the role of Ruby Sue, Cousin Eddie’s daughter. She had previously starred as the Gallaghers’ daughter in Fatal Attraction, the thriller that launched her movie and TV career. Unfortunately, the crew of Christmas Vacation were concerned about Latzen’s mullet haircut, which they felt wasn’t quite right for the character.

Latzen had to wear a long brunette wig for the duration of filming, which she recalled was “super itchy.” Her more memorable moments in the film include when Ruby Sue mistakes Chase for Santa Claus, accompanied by a foul-mouthed exclamation. In recent years, Latzen has created Watched, a podcast about what it’s really like to be a child star in Hollywood.

10. Ellen misstates how many kidnappings the Griswolds have been involved in

As a (misguided) loving gesture, Cousin Eddie takes Clark’s tirade against his boss Mr Shirley a little too literally, and decides to abduct the businessman. With Mr Shirley in captivity, Ellen comically notes that this is the Griswolds’ first kidnapping. But she’s not quite right. The first kidnapping that the Griswolds took part in was in National Lampoon’s Vacation.

In the first film of the franchise, the family kidnap an employee at Wally World theme park. Played by John Candy, this worker is forced to go on a range of the rides with the overly-enthusiastic family. What’s more, in National Lampoon’s European Vacation, Clark and his kin once again become embroiled in a kidnapping plot, this time in Italy.

9. Producer Matty Simmons makes a cameo on a magazine cover

Following his strife with the family Christmas tree, Clark Griswold tries to relax in bed. He tries to read a copy of People magazine, but finds that his hands are too sticky, since they’re still covered with pine tree sap. If you look closely, you can spot that the cover of the magazine is actually a mock-up, created especially for the movie.

The man featured on the cover is in fact Matty Simmons, who produced National Lampoon’s Animal House as well as the first two Vacation movies. In the following decades, Simmons wrote seven books, one of which was entitled Fat, Drunk, and Stupid: The Making of Animal House.

8. A heart-to-heart chat between Clark and Rusty was cut on Johnny Galecki’s advice

According to Rusty actor Johnny Galecki, the film’s writer John Hughes once visited the set and considered putting a heartfelt father-and-son scene back into the script. The first two films had featured such moments, and the original script for Christmas Vacation did, but apparently Hughes was in two minds about including it. Chevy Chase encouraged Hughes to put the scene back in, at which point Hughes turned to the young Rusty actor and asked for his opinion.

Galecki replied that, since the scene had been cut from early script revisions, it would probably get cut from the final film too – and Hughes agreed. Years later, Galecki recalled: “Chevy looked at me like, ‘You just talked yourself out of a scene that John Hughes was going to write for you.’ That was a big lesson. Just from the look on Chevy’s face, I realised I messed up and that I had just ruined a pretty big opportunity for myself by being a little too honest.”

7. Chase liked his pyjama costume so much, he kept it for decades afterwards

In the Christmas Vacation scene where Clark reads in bed, he’s wearing a set of white, red and green pyjamas printed with dinosaurs. While re-watching the film for the first time in years with WhoSay, Chase said he still wears those pyjamas. The actor declared, “I still have them. They’re right in the other room. I haven’t washed them.”

Today, no shortage of National Lampoon’s Christmas Vacation-themed pyjamas are available to buy online, though not replicas of those sported by Chase in the movie. Most of the commercially available PJs feature quotes from the movie (such as Cousin Eddie’s “Merry Christmas! S***ter’s full”) in a festive font.

6. A family in the US decorates their house like the Griswolds’ each year, to raise money for charity

Since 2013, one family in Ohio has decked out their house with Christmas lights to perfectly match the Griswolds’ each December. It is a massive project, involving 25,000 lightbulbs, weeks of work and plenty of help from the family’s neighbours. To complete the effect, the scene also includes a dummy of Clark Griswold, tentatively plugging together two cables while gazing up at the house from the lawn.

For father Greg Osterland, this festive display was something he’d dreamed of having since childhood. “The display does not change much from year to year because we want to stay as true to the movie as possible,” the family summarised on their Facebook page. With this impressive feat, the family raises money every year for the Cystic Fibrosis Foundation by collecting optional donations from onlookers.

5. An untrained squirrel was used to film the dog chase scene

In an interview with Rolling Stone in 2014, director Chechik spoke about an under-appreciated last-minute star of Christmas Vacation: the squirrel. Chechik hired a professional animal trainer and the team was all prepared to rehearse the scene where Snots the Rottweiler chases the squirrel away, when the trainer broke some unfortunate news to them.

The trained squirrel had recently died, most likely of old age. In a frenzy, the production team got hold of another squirrel as his replacement – one with no prior acting experience. They spent a week filming with this chaotic creature. Diane Ladd (Norah Griswold) performed her own stunts in the scene where the squirrel leaps down from a tree, and there were concerns about her being hurt by the wild animal.

4. It’s one of three major 1989 movies with an animated title sequence

Animated introductions were clearly all the rage in late 80s movies – and Christmas Vacation was no exception. Its animated title sequence shows Father Christmas struggling to get into the Griswolds’ house, getting electrocuted by their festive lights in the process. In the background, we hear the song Christmas Vacation, sung by The Staple Singers star Mavis Staples.

It’s the only Vacation film that doesn’t use the song Holiday Road by Lindsey Buckingham. But Christmas Vacation was only one of three major 1989 films to use an animated musical sequence to introduce itself to the cinema. Honey, I Shrunk the Kids and Troop Beverly Hills also use animated sequences as the openings to their live-action tales.

3. It features the exact same truck as Overboard

Amid the star-studded cast, one vehicle in this movie is something of a celebrity in its own right. The truck seen tailgating the Griswolds in National Lampoon’s Christmas Vacation is in fact the very same vehicle used in another 80s classic: 1987’s Overboard. In fact, if you look closely, you can see that Dean Profitt’s carpentry logo has been painted over. In the year after Christmas Vacation, the car appeared in another iconic 80s film: the science fiction classic They Live.

Aside from Cousin Eddie’s notorious RV, few other vehicles feature in this particular Vacation movie. In one scene, Ellen’s father mentions the Griswolds’ spare car, which isn’t shown on-screen – and in the first film the Griswolds did indeed have a second car, a Volvo station wagon.

2. The Griswolds’ neighbours’ house features in all four Lethal Weapon movies

Rather than renting a regular street for this movie, the producers decided that the homes of the Griswolds and their neighbours alike would be filmed at Columbia Ranch. The property where the Griswolds hang their Christmas lights happens to be the same building that is used as Roger Murtaugh’s home in Lethal Weapon, and all three of its sequels.

While the Columbia ranch is probably most famous for housing the fountain seen in the Friends title sequence, you can spot these same settings in the 2009 sitcom The Middle. Funnily enough, Brian Doyle-Murray, who plays the villainous boss Mr Shirley in Christmas Vacation, returned to this set to film as the recurring boss character of Mr Ehlert in The Middle.

1. Rusty borrows one of Chevy Chase’s best-loved gags

When Clark Griswold becomes resigned to the failure of his Christmas light display, he heads off to check each fairy light bulb individually. He asks his son, Rusty, for some help with the laborious task, but Rusty glances at his bare wrist as if he was wearing a watch and rushes off. This gag is a reference to Chevy Chase as a comedian, whose most famous gags include glancing at an invisible watch and making an excuse to leave.

When Clark clambers up the ladder to work on his light display, funnily enough we can see that Chase is actually wearing a watch, leaving the gag open for his on-screen son. As Clark works precariously on the ladder, to the astonishment of his neighbours and family he never suffers a fall. This fact may also amuse long-time Chase fans, who would know Chase is famous for his comedy pratfalls.