Deliberate mistake: In the final scene when the four cars are driving away there is a road sign that shows how many miles it is to Chicago (where the main characters are from). In reality there would not be such a sign because there is not one direct route from Vegas to Chicago. A typical road sign would show the nearest cities.
Vegas Vacation (1997)
1 deliberate mistake - chronological order
Directed by: Stephen Kessler
Starring: Chevy Chase, Randy Quaid, Ethan Embry, Beverly D'Angelo
Genres: Comedy
Factual error: After checking-in at the Mirage, Clark is sitting by his hotel room window admiring the northward view of the strip. Based on the view he must actually be sitting at the nearby Treasure Island hotel.
Marty: You don't know when to quit, do ya Griswold? Here's an idea: Why don't you give me half the money you were gonna bet? Then, we'll go out back, I'll kick you in the nuts, and we'll call it a day.
Trivia: This is the first film in the National Lampoon's Vacation series not to bear the National Lampoon name in the title, as well as being the first without John Hughes' involvement.
Question: How much money did the family win after playing Keno?
Chosen answer: $25,000. Given to the Griswalds by Sid Caesar's character just before he passed away.
Answer: The sign said $30,000.