Factual error: When Tommy goes to Melissa (after the hospital), the porter is refused admittance. In the background, between the '70s cars, emerges a Mercedes from the 2000s on the right corner. (00:56:55)
Continuity mistake: When Tommy picks up his mother's cigarettes out of the toilet, one of them very obviously breaks in half. Yet a few shots later, they are all unbroken and normal.
Continuity mistake: About an hour into the movie, Tommy's face is injured by a shard of glass. The very next shot the injury is almost gone and in the next scene there is no evidence his face was ever injured.
Audio problem: At the beginning of the school dance scene, there is a kid screaming "Sabbath. Sabbath." Later on, the same kid is shown to be the DJ, and when he is changing records, you can hear his voice still screaming "Sabbath. Sabbath." in the background, even though he is not saying it. (Revealed in DVD commentary).
Revealing mistake: When Tommy and Pappass are riding around the city, you can see the same set of 70's period cars in the background over and over, both driving and parked.
Factual error: During a panoramic shot while moving down the street in New York City, a modern-looking Starbucks was shown. It was 1973 at this point in the movie. There were no Starbucks stores in 1973 except one in Seattle. See http://www.starbucks.com/aboutus/timeline.asp.
Answer: It's taken from the score of 'Alive', written by James Newton Howard.
Tailkinker