Continuity mistake: During the campsite scene, the kids take the dog up to see the pool, the scene after has Clarke and Ellen finding their cabins. In the background, you can see the pool with the kids standing there, but the dog is gone. You can see there is no dog when they start to walk down the stairs.
Revealing mistake: At the gas station, while Clark watches the mother and son refuelling the car beside him, she points at her son to remove the gas cap. If you watch closely, he looks like he unscrews it but he has nothing in his hand, and when he "places" it on the rear bumper, in the next shot there is nothing sitting on the bumper.
Visible crew/equipment: When they leave dead Aunt Edna on the patio at the family members' house. While the family is talking you can see the mic above their heads going back and forth when each cast member is speaking.
Factual error: When driving across the bridge entering St Louis, if you look in the rear windows of the car, High Rise buildings are shown. There are no buildings like these in East St Louis. If you're driving from Illinois to St Louis there would be NO buildings in the rear window.
Factual error: The scene at the car lot in the beginning is supposed to take place in Chicago. Mountains and palm trees are visible in one angle when Clark is talking to Ed about the car being the wrong one.
Visible crew/equipment: 2 crew members are visible operating the pirate ship ride.
Continuity mistake: After the Griswolds pick up Aunt Edna, they stop to eat sandwiches from the basket. Chevy sees Christie and flaunts his sandwich. With each shot of Christie, her hair is parted on one side, then the next, then back again.
Continuity mistake: In St. Louis, after the guy asks for five dollars, Ellen says, "That's a fair deal." She turns her head to the right and smiles. The shot cuts to an outside look at the front of the car. Ellen isn't smiling anymore.
Revealing mistake: When they are riding the rides at the end, someone has to be starting and stopping them.
Visible crew/equipment: When Aunt Edna tells Eddie "see I told you he wouldn't like them", Clark closes the door in her face. A film light is reflected in the center of the frame.
Other mistake: In the first gas station scene, Ellen directs Clark to the gas tank opening which Clark has thus far been unable to locate. Despite being a brand-new car, the inside of the gas tank lid is completely rusted.
Factual error: The whole movie he drives without any valid license plate. Just a crooked colored plate from the auto store. He would have been pulled over for that immediately, and the car probably would be impounded. Then when he does get pulled over for the leash, the cop says nothing about invalid plates. But he asks for registration proof and Clark shows it, even though he has no legal plates. Plus his meaningless plate is crooked, which is also illegal.
Suggested correction: The first 30 days after you purchase a new car you don't need plates.
Any place I've lived has required at least temporary plates before the car is actually registered.
The officer still would have to run the VIN numbers to make sure the car isn't stolen. A long time ago certain states wouldn't give you a temporary plate at all, you would only have the dealership plate on the back of the car which would raise any suspicion of law enforcement if they were to get behind you, but no ticket would be issued as long as the car is within 30 days and not stolen.
Other mistake: When Clark and the gang force the security guard onto the "screaming meemy" roller coaster, it starts to roll with no-one operating the controls.
Suggested correction: Every ride they ride would be a mistake as there was nobody to operate any of them.
Revealing mistake: Aunt Edna is supposed to be dead, but look closely as she's sitting in the pool chair, and you can see her upper body move slightly.
Revealing mistake: Christie Brinkley supposedly jumps in the pool naked but she's wearing a flesh colored top that can be seen in several shots.
Continuity mistake: When the Griswolds are lost in Arizona the sky goes from overcast to almost clear during the "jump" scene.
Continuity mistake: When Clark gets pulled over for killing Edna's dog, the sun angle changes constantly, and it even appears the car switches sides of the road. Watch the shadows and the background.
Continuity mistake: The dog changes at least once from when they first get him at Cousin Eddie's to the camp when Rusty has him at the pool. They are two different dogs.
Factual error: As the family is pulling into Coolidge, KS, mountains are visible in the background. Kansas doesn't have mountains.
Continuity mistake: When they are on the looping roller coaster, they come to a point where it is a long drop in to the loop. However, in the next shots of Clark and the security guard, the coaster is going round a curve, and in the next shot it is back on the straight drop.
