Continuity mistake: In the scene in the Beatles hotel room where Nancy Allen comes out from under the cart with the cokes on it, when she first sees the Beatles' guitars, notice that in the very first scene, the Hofner bass is left handed (the pick guard is on the left as you're looking at it), then it cuts to her, then when it cuts back to her rolling on the floor with the bass, it's suddenly right handed, then when in the last scene with her handling it, it's left handed again.
Continuity mistake: When Cheech is turning over his car to pick up Chong you see him starting to turn over before he reach Chong. When it cuts Cheech has passed Chong before turning over. (00:07:40)
Continuity mistake: Throughout the whole film you can see that Rick Danko's bass playing has been completely redone. What he's playing and what you hear are completely different things.
Continuity mistake: Buddy is unloading boxes of tiles in his garage while Riley and he discuss the radio station programming. There are 8 boxes on the shelf and Buddy unloads another two boxes. A minute later, the same two boxes are back in the truck bed, and Buddy unloads them again.
Continuity mistake: It is easy to see Ace Frehley was wearing black leather shirt/pants at the beginning of the film. When they are fighting the robots next to the Rollercoaster, his suit is white leather.