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: 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.
Other mistake: When Senator John McLaughlin is shooting immigrants crossing the boarder, there is only one of his henchmen who is filming with just one camera from one angle. Yet, when this material is shown on TV towards the end of the movie, there are cuts between two cameras from two different angles. The viewer's look (you) is reused as material captured by Mr. McLaughlin henchmen.
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.
Factual error: In a very early scene, just as the young girl is pulling a cellphone out of her vagina, if you look closely you can see that the "cellphone" she is holding is actually an iPod Nano 5th generation, which does not make phone calls.