Revealing mistake: As Machine Gun Joe runs slowly runs over a fisherman in a small brook, he stops and "peels out" on his head. You can see a film crewman in the driver's seat doing the actual carnage.
Continuity mistake: Jonathan explains how to deal with a biker, demonstrating on Blue who's sat on his bike close to the rail. Yet when he's talking to the new guy (Toughie)Blues bike is in the middle of the track and when Toughie comes around the track to attack Jonathan it is back in its original position.
Other mistake: Bronson arrives in town hitching a ride in a boxcar. He hops off and begins walking along a different track. In the next shot, you can see in the background the same freight train he left, already moving in the opposite direction. (00:02:10)