Continuity mistake: When Machete mounts the minigun to the motorcycle in the big fight scene at the end of the movie, it's just the gun barrels and breech on a plate between the handlebars, with no ammo feed. When he's in midair and firing, there is a very visible ammo feed chute going into the side of the gun (as there should be). In the next frame, he lands and gets off the bike, and again it's only the gun/breech assembly, no ammo feed.
Continuity mistake: During the fight in the Hospital, Machete stands before a Guy just watching him. In the next scene the police Officer gets shot. Back to the Scene with Machete still standing there watching the guy before cutting his belly. It's like Machete is standing watching this guy for 5 seconds without moving during a fast fight with more than 3 guys.