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: 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.
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.