Factual error: The introduction of the film has Alexandria (331BC) on the map, but the timeline is several hundreds if not thousands of years prior to then.
Revealing mistake: In the scene where the group of unlucky virgin sacrifices make it to the Minotaur's sleeping chamber and are banging on the door trying to get out, one of them is gored and lifted into the air. When this happens you can see the harness and wires (the cables are about 1/2 an inch thick and black, one either side of the body). In the same shot the clothing of the gored victim is bunched up over the cables also. (00:47:40)
