Deliberate mistake: When the truck is slamming numerous parked cars on a residential street, it sideswipes a parked Dodge Aspen (white with tan landau top). At the lower-right corner of this shot, a white Chevy Nova is parked at the corner (its vinyl top and trim has been poorly painted the same white as the body). Both these cars are repositioned to be at the roadblock location at the end of the chase, with the Nova slammed from behind by the truck and the Aspen parked near the cop cars. (00:07:00 - 00:07:40)
Deliberate mistake: When the geek and the prom queen are driving along in the Rolls-Royce rebel yell scene, the close-up shot of them through the windshield shows a missing rear-view mirror. It was there when the geek pulled out of Jake's garage and it reappears later when the Rolls is parked in front of the house where John Cusack's character lives. This was probably a deliberate mistake by John Hughes so that he could get a better shot of the prom queen feeding birth control pills to Anthony Michael Hall.
Deliberate mistake: In the end sequence, when the joyous Valley of the Wind people run past Yuppa and the old woman to welcome back Nausicaä among the living, the same group(s) of people are seen twice running from the right to the left.
Deliberate mistake: As David runs from the MP's in the restaurant, he jumps off the balcony onto the bar below. It is very obvious that it's the stunt double for Michael Pare doing the jump. (00:45:35)
Deliberate mistake: Before going on stage in the infamous purple coat for the first time in the movie, the Kid is in his dressing room. The silver jewelry/decoration on his coat is on the left shoulder. In all subsequent shots, the silver jewelry/decoration is on his right shoulder.