Continuity mistake: At the beginning of the movie, when Clark is driving down the street looking at the map, there are 4 kids roller blading in the street. In one shot, one of the kids jumps onto a parkway lawn to avoid being hit by Clark's bad driving. Next shot, when they pan back to the kids, all 4 are still on the street.
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.
Continuity mistake: When Eddie and Clark are at the buffet, the cook has the two pots of chicken and beef, but the signs are in the wrong place. So he picks up the chicken and places it in the spot where it is supposed to go. He is about to put down the beef sign where it's supposed to go, and you see him pick up the chicken sign AGAIN and place it in the right spot, as well as the other sign.
Visible crew/equipment: At the beginning of the movie when Clark is entering his house and the camera angle is from inside, just as he opens the door there is something red on his front porch. If you look at any of the previous scenes, that red thing isn't there. It's the bottom of a sunscreen being used to block the bright sunlight (which would have flooded the camera) behind Clark as he enters the house. (00:01:44)JamesP
Audio problem: When the whole family is at the Siegfried and Roy show Clark is asked to participate and they make him disappear and he doesn?t come back. At one point Rusty says "I wonder where Dad went" and Ellen responds with "I don't have a clue". If you read Ellen?s lips she is actually saying "I don?t know" and waves her hands. (00:20:21)JamesP
Continuity mistake: Clark gives the blackjack dealer $200 and asks for chips. Even though the dealer never give him any chips, in the next shot we see he has chips in front of him and he's already placed one in the bet area. In the next shot the dealer asks him to place his bet and we see that the amount of $5 and $25 chips in his stack far exceeds $200. (00:14:50)
Continuity mistake: When Rusty Griswold first gets his fake ID, he walks in to the Riviera Casino and goes up to the bar. When he tries to order a drink, the bartender asks for ID, right when he is doing this, he lays down a napkin, and then the scene switches and he lays the same napkin down in the same place again.
Continuity mistake: When the mom is with Wayne Newton, after she was covered with pasta, she has a noodle in her hair. Later we see it dangling in front of her face to look more messy.
Continuity mistake: At the beginning of the movie when Clark is driving home, he skids into his driveway where it is visible that the Ford Expedition is crooked and about three feet from the bike. In the next scene the Expedition is straight and right next to the bike, so that he steps on it when he gets out. (00:01:21)JamesP
Continuity mistake: At the beginning of the movie when Clark and his family sit down at the kitchen table to talk about their Vegas Vacation, watch the fruit basket in the middle of the table. It's there when they go to sit down and it's gone in the next scene. Every time it shows the kids it's there and every time it shows Clark and Ellen it's gone. (00:02:32)JamesP