Revealing mistake: In the part it shows Ash getting sucked into the time portal you can see the wire he is hanging from.
Continuity mistake: Ash has his shotgun stolen from him by the mini-Ashes who use to shoot at him. Ash then runs outside (all the while splitting into his good and bad halves) leaving his gun inside the windmill. Moments later Ash now has his shotgun again so he can blast Evil Ash in the face.
Visible crew/equipment: In the scene where the deadites are invading the drawbridge, a person gets slashed by a guy on a horse. When he falls, if you look quickly enough you can see the end of an airbag come up under the bridge.
Continuity mistake: When the witch falls the ground, playing possum, she is lying with her head away from Ash and Arthur, but when she jumps up, her head was where her legs were.
Continuity mistake: When Ash is in the pit, he grabs the chain that is moving that causes the spikes to come together. However, when he finally pulls himself up, the chain is attached to a spike in the ground. How was the chain moving?
Visible crew/equipment: In the scene where Ash first goes to the graveyard where the Necronomicon is said to be located, for the first second of the third shot of the camera "chasing" Ash, in the lower lefthand corner you can see the booted foot of the person carrying the camera.
Continuity mistake: When Ash is driving his modified car crushing skeletons and such, a skeleton jumps on the side of his car. Ash shoots him with his shotgun and A) the shot from the shotgun is it front of the skeleton (not hitting him), and B) when he says "Bye Bye", his mouth does not move.
Continuity mistake: At the beginning when the wise man says to King Arthur something along the lines of, 'I believe he is the one written off in the Necronomicon. He who has been prophesied to fall from the sky and deliver us from the terror of the deadites,' He is sitting on the horse to the right of King Arthur. When King Arthur says, 'What? Who? Likely he is one of Henry's men,' the wise man is now on the other side of Arthur.
Continuity mistake: Before Ash flies through the vortex, you will see that he does not have a watch on his left wrist. Later he has a watch on his left wrist after he passes through the vortex.
Continuity mistake: When Ash falls through the portal he has his gun, and after the King's men seize him it's knocked out of his hand. After the King draws his sword to challenge Ash to combat, Ash shoots the sword with his gun. How did he get it back so fast?
Continuity mistake: When Ash emerges from the Vortex, he falls on what looks like mats. When he coughs, the mats are gone.
Factual error: When all is back to normal and Ash is back at his job at S-Mart, a witch shows up and starts trashing the place. Ash is knocked behind the sporting goods counter, where there is (of course) a cabinet containing guns. Ash then jumps up and blows the witch away, firing 37 times. He's using a .38 caliber Winchester Model 1892 Saddle Ring Carbine with a "Trapper" loop lever. It only holds 9 rounds.
Deliberate mistake: Ash's car breaks out into the courtyard and the whirling, windmill thing batters the Deadites aside. We see the carnage a couple of times filmed from different angles, one Deadite, planted, legs apart, gets battered twice and the guys who come in from the left and are quickly jerked off screen are shown again seconds later.