Continuity mistake: When the family is getting into the car to go to the wedding one grandmother says to the other "let me in". The grandmother gets out to let the other grandmother in but the first grandmother never gets back in the car, she just pretends to. You can see her hiding behind the cars as it backs down the drive. Both grandmothers are in the car when they see Long Duk Dong on the lawn.
Continuity mistake: The guy with the red Star Trek glasses is standing behind Sam and Randy as they walk in at the beginning of the dance, and he is staring at the scoliosis girl (Joan Cusack). Then in the next shot, he is standing with the geeks on the other side of the gym. You don't see him walk away at any time during the sequence when Sam and Randy are talking. How did he get over there?
Continuity mistake: In the opening shot of Jake's party, a girl wearing a light, multi-colored dress is sitting on the back of the sofa talking to a guy in a blue t-shirt. In the close-up of Jake, as he enters the room (with a disgusted look on his face) the girl is now sitting at the front of the sofa chatting with the prom queen, who was not there before.
Continuity mistake: When Samantha and Randy are getting on the bus, they both scan past the juvenile carnage to the back of the bus where the adolescent band is practicing. The geek is nowhere to be seen. However, when they take their seats, the geek immediately appears behind Samantha at the back of the bus leaning on a trombone case.
Continuity mistake: When Long Duk Dong comes speeding out of the parking lot after the dance, there is only one other person in the car with him and he is not wearing any sunglasses. When the shot immediately changes to a close-up through the windshield, there are now two other people (Samantha and the sexy girlfriend) in the car and The Donger is wearing sunglasses.
Continuity mistake: At the party we see Long Duk Dong and sexy girlfriend crash Grandpa's car into the front yard with a drive-in window tray attached to the driver's window. The scene prior to this was them at a drive-in restaurant eating and causing a ruckus, but this scene was cut from the final film. This is a typical continuity error when prior scenes are cut from the final film.