When Eddie and Rick Diesel are practicing on guitars to a taped track, you see both characters smoking cigarettes. Rick Diesel's cigarette is obviously lit and there is smoke coming out of it while he is playing. Towards the end of the scene, another close up of Rick shows the cigarette not lit at all. When the camera pans back onto him a moment later, his cigarette is lit again.
During several performances, the music does not sync with the band members' actions.
When Eddie drives from Montreal into Manhattan, he drives over the Brooklyn Bridge. That would be a very indirect route.
In a flashback, Eddie is on the beach in New Jersey telling a band member what he wants his music to be like. He uses bedsheets as an analogy. In the original movie, he's talking to Frank Ridgeway (Tom Berenger). In the sequel's flashback, he's talking to Sal Amato (Matthew Laurence).
Bo Diddley describes Lakehurst, New Jersey as a little town right outside Newark. It's actually far south of Newark, west of Toms River.