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: When Rusty takes his fake ID photo, he places his right hand directly over some numbers on the bottom of the "license." In the next shot, his hand has moved over significantly.
Continuity mistake: When Clark is checking in at the hotel, he puts down his credit card twice.
Continuity mistake: In Rusty's last craps scene, the croupier pushes the dice to him but Rusty picks up several chips instead - not the dice. Rusty immediately rolls the dice without having picked them up.
Continuity mistake: In the Keno scene, after Ellen fills out the Keno card, she gets up and walks to a counter to turn in the card. While that is happening, Clark has a conversation with Mr. Ellis. During close-ups of Clark during the conversation, Ellen's shoulder and the shiny sequined dress she is wearing can be seen next to Clark. Ellen is there one moment, gone the next, back again and then Ellen is shown returning from the counter to her seat.
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 the Griswolds get into their hotel they meet their parents at the intersecting door Audrey is pictured by the door frame but the camera cuts off and she is sitting on the bed.
Continuity mistake: When Clark gives Rusty and Audrey 20 bucks each, between shots of him giving Audrey her 20 bucks, her hands moves down.
Continuity mistake: Eddie (Quaid) takes Clark (Chase) to the casino buffet for dinner. As they fill their dish with food, Clark tells the server behind the buffet table that the chicken and beef dishes are labelled incorrectly. The server then switches the tags, placing them in each dish. In the next scene he repeats the switch.
Continuity mistake: When Clark first meets Marty at the Blackjack table, he is dealt a hand. If you look closely at the cards, they change suit and number from when they are dealt to when the hand is over.
Visible crew/equipment: The camera and the cameraman are reflected in the chrome of the Griswold limousine when they are driving down the strip.
Continuity mistake: Right when the guy dies at the end he's leaning straight up against the chair, but the next shot of him, he is leaning to the left.
Continuity mistake: In addition to the submission regarding the tour van acquiring damage to the hood after crashing through Wayne Newton's house, the mirror on the drivers side is bent. In the next shot when Clark exit's the vehicle and closes the door, the mirror is gone.
Factual error: Rusty couldn't take possession of the cars without paying for tax, title and license fees. They wouldn't be sitting at his hotel ready to drive away.
Suggested correction: Maybe he did all that with his fake ID and casino winnings off screen?
Continuity mistake: At Hoover Dam, Clark pulls out a small rock and causes a little leak. While he's fixing, it another develops. He puts his left side against the second leak to hold it until he gets the gum in the hole. The water stain on his shirt changes from his left side to his right side, then eventually his entire shirt, in different shots.
Visible crew/equipment: When Clark asks for Audrey and Russ at the door, there's a production member reflected in the mirror behind Clark, right before he walks in front of the television to watch the commercials.
Visible crew/equipment: In the scene where Audrey is dancing on the sign with her cousin, you can see the safety cord in the shadow when she is at the top.
Continuity mistake: In continuity of Rusty's fake ID lacking the Vegas background, both his right and left hand are covering significant parts of the text in the oversized ID he is holding which doesn't appear in the copy of the ID.
Continuity mistake: When Clark is getting breakfast and he is reading Card Counting, at first, you see him holding the book by the sides, then you see he is holding it by the bottom middle, then the sides again.
Continuity mistake: When Russ takes his fake ID picture on the street, and he sticks his head in the giant license and there is no backdrop behind his head...you see Vegas light behind him.. but when the casino guy checks the fake ID, it is all white behind his head... no Vegas lights.