Continuity mistake: The slice of pizza on the disco guys' windshield changes from shot to shot. In the close-ups, there are hunks of cheese and drippy sauce splattered all over with crust, yet, in the wide shots the windshield is cleaner, with just a small triangle of crust.
Other mistake: Lex is in the backstage area and is being chased by a guard. He is walking around carrying a piece of drum equipment and he trips over a cord and drops it. But when the camera shot changes back to him the cord is nowhere to be seen, therefore he really tripped over thin air.
Continuity mistake: In the scene where Lex, Trip, and Hawk are in Lex's basement getting ready to go to school, there is a closeup of Trip hooking on a chain to the side of his jeans. In the next shot, the chain is hooked on to the front of his jeans.
Continuity mistake: While the four guys are on their way to Detroit, Trip is hanging out of the sunroof. In the next few shots, you can clearly see that the car has no sunroof for Trip to hang out of. [The Volvo does have a sunroof the whole time, it is actually a moonroof with clean lines that are hard to notice.]
Revealing mistake: When Jam answers the telephone he falls, and when the telephone falls too there's no cord in it.
Revealing mistake: When Hawk pukes on the stage you can notice in the side view that the puke is too much and fake.
Continuity mistake: The brake pedal on the Trans Am is first shown with chrome trim around it when the driver stomps on the brake to cut off the Volvo. When the rock is put on the gas pedal to send it into the ditch, the brake pedal is seen to have no chrome trim.
Factual error: In the beginning when Mystery is practising there's a close-up of Jam's bass drum and judging by the indentations and shape the basshead is on very loose. That would mean the strokes would be very sloppy and resonant, but the beats we hear are sharp and hard.
Continuity mistake: When Jam is talking to Hawk on the phone and Jam says he's sorry, the tone of voice and look on his face changes from one frame to another when he says "See ya guys at school."
Factual error: The Pizza Pig delivery driver arrives to the parochial school in a pink Lada Niva. Russian Ladas have never been imported into the States, and though it may be argued it have been purchased and brought into the US from Canada, since Canada did import them for awhile, the Lada is a late 80's model, and the movie takes place in 1978.
Factual error: The song the disco fans are singing along to before the pizza hits their car is "Makin' It". this would be impossible as the film is set in 1978, and the song was not released until 1979.
Continuity mistake: While the disco guys are beating Hawk and the others the sun changes between shots.
Factual error: When Beth is looking out the school window at Jam's Mom driving away with him leaving the school, at the top of the screen is an adjacent street and one of the cars passing by is a Chevrolet Venture minivan, which didn't come out until the mid 90s. (Note: this error has since been cropped away from DVD and Blu-ray versions and is only visible on the VHS release).
Factual error: The movie is set in '78, however the Volvo has plastic hubcaps which were not available on Volvos until 1986.
Answer: It is the intro to Black Sabbath's "Iron Man".
Twotall