A Hard Ride to the Movies (1972)

A San Francisco biker gang, the Frisco Savages, learn that Hollywood producer Max Green is making a biker movie, "The Bloody Bikers", and they decide that they should be in the movie, since they are the real thing. So they head off to LA, picking up two other people en route. Once in LA, they learn that everything about Hollywood is, like, totally phony, man.