Factual error: Set in the summer of 1977, serial killer David Berkowitz is seen throughout the film wearing a US Army woodland camouflage pattern field jacket. The Army did not start using these jackets nor were any ever made until the early 1980's. They were all solid green until then.
Factual error: Near the beginning of the movie, which is set in 1977, the song "Grace of God" is playing in a club. "Grace of God" didn't come out until 1979.
Factual error: There is a scene where Vinny is holding a pack of Marlboro Red cigarettes in a box. On the side of the box you see Marlboro Miles. The film is based in the 70s and Marlboro Miles weren't introduced until many years later.