The original ending of the film consisted of the Griswold family, after seeing that Walley World is closed, going to the Hollywood house of Roy Walley (Eddie Bracken). Clark points a BB gun at Walley then forces him and his business associates to sing and dance Walley World theme songs before the police arrive to arrest Clark. The Girl in the Ferrari turned out to be Walley's daughter and she convinces him not to press charges against Clark. On the plane ride home, the Griswolds realize they are on the wrong flight. Clark snaps and hijacks the plane. This did not go over well with test audiences and the scenes in the park with John Candy were a last-minute alternate filmed over two weeks, four months after production ended. The original ending was deleted and is believed to be lost. A photo of the Griswolds on the plane is shown during the end credits.
As the Griswolds are leaving Chicago, you can see the Buckingham fountain (a popular attraction in Chicago's Grant Park used in the intro to Married with Children (1987)) in the background at one point.
There was a Walley World Water Park in London, Ontario, Canada, which opened several years after the movie was released. John Candy was invited to the opening of the park but the park owners couldn't afford his appearance fee.
Exterior filming of the Griswolds "on the road" took the greater part of three months during production, crossing numerous states including California, Arizona, Colorado, Misouri and Illinois, which was filmed by a second unit. While most of the principal filming took place in California, the cast did travel on location for scenes set in Colorado, Utah and Arizona.
The theme park that served as Walley World was actually Six Flags Magic Mountain in Valencia, CA. The roller coaster referred by Clark as the "Whipper Snapper" is actually called "The Revolution" and was the first roller coaster to have a 360-degree vertical loop.
Apparently, it was originally scripted that after Aunt Edna was tied to the roof of the car, there was a shot of her fingers moving implying she was, in fact, still alive. This was considered "cruel" to have a live person on the roof of a car by the ratings board, so it was cut and she remained dead.
The scene where the station wagon goes airborne in the Arizona desert actually caused some production changes due to the hard nose-landing that wasn't expected. Among those were matching the exact front-end damage on other station wagons used in other scenes.
In the Walley World scenes near the end, Anthony Michael Hall is taller than Beverly D'Angelo; in previous scenes with her he was the same height as her. This was because Hall grew three inches after principal photography finished; the ending was re-shot four months afterward, because the original ending failed with test audiences.
Imogene Coca originally turned down the part of Aunt Edna because she did not think she could portray such a mean character. Even during filming, she was often concerned that she was being (too) mean to her fellow cast members.
The gas station and sporting goods store where Clark pulls into and purchases his BB gun were located at the intersection of Ocean Ave. and Santa Monica Blvd. in Santa Monica, CA. Both buildings have since been torn down and replaced by apartment high-rises.
In the DVD commentary, director Harold Ramis mentions that for the scene in which the Family Truckster jumps into the air, several of the crew members had made bets against 2nd unit director Dick Ziker that he couldn't jump the car more than 50 feet (even drawing lines in the sand to measure the distance). Ziker ended up winning that bet, as he jumped the car more than 50 feet.
In the DVD commentary, Chevy Chase mentions that the scene in which Rusty puts his feet up on top of the driver's seat was originally not in the script, but the producers liked it, so it was kept in the movie.
Director Harold Ramis said in the DVD commentary the scene where the Griswolds get off the wrong exit in St. Louis and get lost in the ghetto was one of the most politically incorrect sequences he ever shot and that it practically demonized everyone involved. He also admitted that he wasn't proud of shooting it the way it appears in the film and that he was not even sure if he would shoot that particular scene today, and if he did, he would shoot it or write it out in a different and more politically-correct way.
For the scene in Dodge City where Clark taunts the ornery bartender who ends up shooting him with a blank-loaded rifle, one of the prop guys ended up playing a practical joke on the cast members during one of the takes. During that particular take, after the bartender shoots at Clark, the prop guy tossed down a fake dummy from the second level of the set and the entire cast jumped in surprise afterward.
There were two scenes which were in the original script and shot but were cut from the final version of the film. One scene had the Kamp Komfort manager (Brian Doyle-Murray) dress up in a moose costume and sneak into Clark and Ellen's tent to scare them (which explains the "wildlife fun" the manager mentioned as they checked in). That scene was cut because it made the sequence run too long, so it was re-written to have Dinky sneak into the tent instead. The second scene originally written/filmed but cut was one featuring the two Indians (the same ones who see Clark wandering aimlessly through the desert and say "What an asshole") as well as a camel rider who finds Ellen and the rest of the family and rescue them. That scene was cut because,e according to director Harold Ramis, the camel had been raised in Burbank and had only ever walked on pavement, and the camel did not take to walking on hot sand very well. All the shots of the camel were unusable. Remnants of both cut scenes appear as photos during the ending credits photo montage.
For the scene where Clark ties Dinky's leash to the rear bumper and forgets all about it before driving off, producer Matty Simmons said that after the movie's release, he received numerous letters from people who had seen the movie and admitted that they had made the same grievous error with their pets as Clark did in the movie.
According to director Harold Ramis he cast John Candy in the role of Laskey the Guard because he had enjoyed working with Candy on SCTV (1976) (aka SCTV, Canada's version of Saturday Night Live (1975)) and that he also loved Candy's "Paul Fistinyourface" character from the show. Ramis had Candy play the character as a sort of relative to Paul Fistinyourface. Also worth mentioning is that Eugene Levy (the car salesman) also worked with Candy and Ramis on SCTV.
All the cast members had terrible experiences when it came to filming the scenes inside Walley World, where they rode all of the roller coasters and other rides. In the commentary, Chevy Chase mentions that many of the rides made him and the other cast members sick to their stomachs, especially since they all had to ride them several times for each take. Dana Barron mentioned in the commentary that the coasters made her so sick she had to take motion sickness pills and would pass out on nearby benches between takes. Finally, Anthony Michael Hall mentions that in the shots on the roller coaster where he looks scared, he wasn't acting--his fear in those shots was genuine.
When Clark drives to the sporting goods store after leaving Walley World, the Truckster makes a hard left through a red light and nearly hits an oncoming Ford LTD Country Squire station wagon--the same vehicle from which the Wagon Queen Family Truckster was modified.
On February 7th, 2010, Chevy Chase and Beverly D'Angelo reprised their characters from this movie in a Super Bowl ad for the vacation rental website HomeAway.com and even the Wagon Queen Family Truckster made a appearance in the ad as well. Following the Super Bowl, the website also featured a 2-part Vacation mini-movie called "Hotel Hell Vacation".
According to Rena Fruchter's 2007 biography "I'm Chevy Chase...and You're Not", both Harold Ramis and Chevy Chase did uncredited rewrites of John Hughes' screenplay, shifting the focus from the teenagers to the parents. For instance, the Ferrari Girl was originally to be a 13-year-old love interest for Rusty instead of Clark.
When Clark brings home the new car and drives up to their house in the "family truckster" the house next door features a tower with a large "beam" (also known as a "Yagi") antenna. This type of antenna is widely used by amateur (ham) radio operators to communicate worldwide via shortwave.
Both Chevy Chase and James Keach stated in interviews that during the "Dog tied to the bumper" scene, both he and Chevy Chase were legitimately tearing up and that Chevy consistently biting his lips and his shortness of breath were genuine; all because they were trying so hard to contain themselves from laughing.
There was a deleted scene that took place after those 2 redneck mechanics clean Clark out of all his money for the car repairs and Clark mentions that they're going to run out of gas. In the deleted scene, they do run out of gas and Clark, Ellen and the kids are forced to push the car(with Edna still inside it) to the nearest gas station. The attendant fills the car up with gas and then Clark drives away very fast without paying for the gas because he has no money. The attendant then runs after them on foot but of course doesn't catch them. That gas station is also where Clark got those sandwiches because later after leaving the Grand Canyon motel, he tells Russ to get out the sandwiches he got at the gas station.