Trivia: Not a mistake but a "before they were famous": little cousin Vicky with the blonde hair is Elaine on Ally McBeal (Jane Krakowski).
Trivia: The script was based on writer John Hughes short story called "Vacation 58" which was based on a real life trip he took as a child with his parents in 1958.
Trivia: When Clark and his family finally reach Wally World only to discover that it is closed for repairs, the voice of the apologetic recorded message from Marty Moose is that of the film's director, Harold Ramis.
Trivia: Russ is older than his sister Audrey in the film, but in real life Anthony Michael Hall is two years younger than Dana Barron, who was 16- 17 at the time the movie was undergoing production.
Trivia: Harold Ramis' voice can be heard as a member of the SWAT team telling Roy Wally, "Everything is wrapped up here" just before Roy decides not to press charges.
Trivia: Lorenzo Salviati, Beverly D'Angelo's husband at the time, has a cameo as the musician playing the piano at the bar during the scene where Clark meets up and chats with the Ferrari girl (Christie Brinkley).
Trivia: Daisy Mabel Johnson, the daughter of Eddie and Catherine who was born without a tongue, is portrayed by Violet Ramis, the daughter of the film's director, Harold Ramis.
Chosen answer: The parking lot is huge. There's really not any way to close the lot itself, but even if there were gates, Clark would probably have been oblivious to them by then.