Factual error: In one scene a parked car is sitting along the street - it is a '68 Chevy, it has sidelights. Yet the film is set in 1962.
Factual error: In one scene, Milner does a U-turn and you see a postal box on the curb. The logo on the box is the current white eagle drawing, but that was not used until well after 1962.
Continuity mistake: In close ups of Milner driving, watch the rolled up package of cigarettes in his T-shirt sleeve. In different shots you can see the front of the pack and the back of the pack, when there has not been time for him to have another.
Visible crew/equipment: As Milner and Carol get out of his hot-rod to vandalize the girls' stopped car, a bearded man with a mustache can be seen in the car window's reflection as it's being rolled up. The man is wearing a white long-sleeved shirt with what appears to be a maroon sweater-vest. I believe the man to be George Lucas, as he appears to be directing in an upward motion with his left arm. (00:59:05)
Continuity mistake: When Toad turns the 58 Impala around to pick up Debbie. She walks past the same Blue Corvair twice. She then steps from the curb to talk to Toad. The Corvair is parked next to the curb. When they switch to the long shot the Corvair has been replaced by a gold coloured Buick. When they drive away the Corvair reappears in its original position.
Continuity mistake: The girls - whose car tires are about to be flattened and windows about to be sprayed with shaving cream - roll up their passenger window twice during the same brief scene. Once as Milner and Carol are getting out of his hot-rod, and again as John and Carol approach the car. (00:59:00)
Continuity mistake: After Carole is hit with the water balloon thrown from a passing car, she tells John Milner to catch them at the light, where he's to flatten their tyres while she sprays the windshield with shaving cream. Carole sprays the front windshield, then starts to go to the back of the car to spray the back window. The front windshield is clean, even though Carole just emptied a can of shaving cream onto it.
Continuity mistake: When the '55 Chevy crashes, it comes to rest upside down with the trunk lid open. Moments later when it bursts into flames, the trunk lid is closed.
Factual error: Shortly after Milner picks up Carol they make a right hand turn off the main street. There is a White 1971 Toyota Corolla at the intersection directly in front of a white 1960 Pontiac. The movie takes place in 1962.
Deliberate mistake: The Studebaker in which Carol is first riding bears the license number JPM 351, which interestingly enough, is not only the same license number that Steve's 58 Chevy has, but is also worn by the car Curt is sitting on when he first meets the Pharaohs. To top it off, the Edsel driven by Cindy Henderson has plates reading PRC 596, which are also used by a silver 57 Chevy and a red pickup.
Other mistake: In the race scene between Milner and Falfa, you can see exhaust smoke coming from Milner's car, but in a previous scene the station attendant mentioned Milner taking the header plugs off. By taking the header plugs off, his exhaust is running from the headers and you wouldn't see exhaust coming from the tail pipes. (01:03:15)
Other mistake: When Carol leaves her car full of girlfriends to get into John Milner's yellow coupe, she does not reach for his obvious door handle, but instead puts her hand through the open window and uses the inside release. She could not possibly know the outside handle would not work.
Continuity mistake: During the first set of cruise scenes, you can see a shot of a yellow '56 Chevy parked on the opposite side of the street with the hood raised and a coupe of guys working on the engine (just after a purple-ish '40 Ford rolls past). In the very next shot, you can see the same car for a very brief moment, this time with the hood down. A few shots later, you see the same yellow '56 yet again, but this time being driven. Finally, in the very next shot, Milner drives past it yet again, still parked on the side of the street, with the hood down. (00:10:14)