Continuity mistake: When the family sits down at the table and the camera pans back and forth from Audrey and Rusty to Ellen and Clark Audrey's hair is in front then it's in back and it changes about nine different times.
Visible crew/equipment: In the beginning of the movie after Clark trips over the bicycle in his driveway and approaches his house you can see the microphone in the upper middle of the screen momentarily.
Continuity mistake: When they are at the Wayne Newton concert, and Wayne starts walking towards Ellen, when you see a back shot of Clark and Ellen, you see Clark looking towards Ellen, but in the next front shot of them, he is looking straight.
Continuity mistake: When the guy says "take the ticket at the end" and then drops it, the ticket changes in all of the shots that you see it.
Other mistake: If you watch closely when the Griswolds approach the limo driver at the airport, you will see a pilot with glasses walk by in the background, and he sticks his tongue out at the camera and looks right at it.
Continuity mistake: When the mom is with Wayne she gets covered with pasta. In the next sequence she is running down the hall with Chevy Chase looking for Rusty where she still has noodles over her right shoulder. as soon as she steps into the room the noodles have disappeared.
Continuity mistake: In the Hoover Dam scene, the tour group is walking through an underground tunnel when Clark messes with the wall and more water than normal starts coming out. He gets gum from Audrey and starts plugging the holes. He puts gum on the first hole and when the gum makes a bubble filling with water, he puts another chewed piece on the bubble. In the next shot, there is no piece on the bubble and he puts a chewed piece on another hole in the wall.
Factual error: Near the beginning, it's clear we're in Chicago because we're hearing a Chicago radio station. Clark turns the corner before nearly running into people in the road. You can see mountains in the background very briefly. The Griswold house was one of the properties on the Warner Brothers Ranch in Burbank, California which has since been demolished.
Other mistake: While touring the dam, Catherine (Ellen's cousin) mentions that Eddie told her that they'll get electricity some day. But earlier, we saw a working refrigerator (with a light that went on and off) in the trailer's kitchenette. When Eddie and Clark are digging for the buried money at night, we also see lights on the trailer's exterior.
Continuity mistake: At Cousin Eddie's "house", right before they go to Hoover Dam, in one scene a noticeable dust storm is happening but in the very next shot, its not.
Visible crew/equipment: When Christie Brinkley is keeping pace with Clark in her sports car, the camera vehicle is reflected in the passenger side window of her car. It's not the Griswold's minivan.
Other mistake: In this film, the oldest son of Catherine and Eddie is named Denny. In the original film, his name was Dale. He looks the same (although a different actor used) so it's under the assumption it's the same kid.
Continuity mistake: When Sid Ceaser is fake-dying near the end, his head rolls backwards. In the next shot his head is on his right shoulder.
Continuity mistake: When Clark and Ellen are on the plane and go to the restroom to join the mile high club. Ellen goes to the back of the plane while Clark goes to the front.
Other mistake: When Rusty put coins into the slot machine to win the first car, he only put in 2 coins, but if you look closely at the payout table, he would have had to put in 3 coins to win the car. The same thing happened when he won the Viper. Also, when he won the Viper, the light on the top of the slot machine did not flash on and off, which would have happened if he had any type of big win.
Other mistake: At the end of the movie, there is a sign that says "Chicago 1880 miles." First, it's not 1,880 miles from Las Vegas to Chicago, it's closer to 1,750 miles, but also the road they were driving on was heading west, so they would have ended up in California.
Continuity mistake: When the family is on the airplane on their way to Las Vegas, Mrs. Griswold has her purse strap over her shoulder. In the next shot there is no strap. Later on when she is going to stand up, she takes the purse which is lying next to her and not over her shoulder.
Answer: The sign said $30,000.