Continuity mistake: When Machete is picked up by Booth in the S-class, the car changes from an S500 to an older generation S-class, and then switches back for the rest of the film. The footage was from the trailer being edited in.
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: After Machete's failed sniper shot on the roof-top, he is chased onto a rooftop where he kills a bunch of people. After he has killed everybody a splat of blood randomly appears on the ground.
Continuity mistake: At the final battle between Machete and Torrez, Torrez just has one samurai sword when untying the ICE agent and in the next shot he is suddenly holding two samurai swords in his hands.
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.
Continuity mistake: When Machete sets up to shoot Senator John McLaughlin he takes the cap off the scope far from him but leaves the other end on so when he is looking through the scope his end cap is still on.
Continuity mistake: After Machete flees, and Rivera picks him up, her BMW's license plate is different after the handbrake turn when he tells her about the second shooter.