Factual error: The movie is set in 1971, but during the start of the motorcycle race several of the bikes are obviously early 90's Honda CR's and Suzuki RM's. You can tell this from the disc brakes on the front wheels of the bikes and the 90's style plastic fenders and bike colors. Bikes in the 70's generally had metal fenders and definitely no front disc brakes.
Trivia: In the flashback scene where Johnny Depp is taking LSD in the bathroom of a 60's bar, a guy who is dressed like a hippy, walks in, asks what he's doing and starts to lick the LSD he had dropped in his red flannel shirt. That guy is none other than Red Hot Chili Peppers bassist Flea.