Continuity mistake: During the movie, you can see that the metal handle of the chainsaw switches between being thin and thick. This is because they had replaced the handle half way through the shoot and had just painted the regular one silver and brown.
Other mistake: When Evil Ed picks up Jake and throws him headfirst into the lightbulb, watch the speed that he hits it and then falls away from it; he moves far to slowly.
Factual error: In the "Groovy" shed scene, Ash holds a double-barreled shotgun in one hand and saws through the gun barrels with his newly-mounted chainsaw in about 2 seconds flat. He could no more cut through a hardened steel shotgun barrel with a chainsaw than he could cut through a marble counter-top with a butter knife.
Visible crew/equipment: When Linda's headless body is chasing Ash through the tool shed, at some points you can see the stick that's holding her muppet-like body. Also, at one point you can see the hand holding it up. (It is very visible after she gets the chainsaw in her neck and Ash is trying to beat her away. Easiest seen in slow motion.) (00:21:00)