Continuity mistake: The lit flashlight dropped on the floor by the soon-to-be beheaded victim disappears in subsequent shots.
Revealing mistake: The headless motorcycle rider's torso and arms are not in proportion to a real motorbike rider. The torso is obviously made larger to accommodate the stunt bike rider.
Revealing mistake: The pre-cut hole in the garage door is visible before and after the motorcycle busts through it.
Continuity mistake: When the headless biker attempts to run over Studs Spake, the biker crosses in front of the prone Spake. The instant shot then shows the biker crossing again, but this time behind Spake.