Continuity mistake: In the scene where Lily is hiding behind Thomas' computer desk, she uses her little Eiffel tower necklace to put inside the socket to short out the power. When she goes to put it in, you can see the computer is plugged in on the bottom socket. After a really quick cut scene, the computer is now plugged in on the top socket. (01:05:00)
Factual error: Colonel Meyer's promotions are listed in his SS ID card as Hauptmann, Oberstleutnant and Oberst. Since the SS used a different ranking system from the Wehrmacht, they should actually be Hauptsturmführer, Obersturmbannführer and Standartenführer.
Revealing mistake: As the guy is being pinned down by the giant hooks you can see for over a minute he can simply escape and slip his hands out. (00:52:30 - 00:53:30)
Factual error: In his crude attempt to replicate the Human Centipede surgical procedure, Martin employs several handyman tools, including a carpenter's staple gun (using T50 staples as sutures). Problem is, carpenter's staples would never join soft human body tissues, they'd pull right out with little effort (T50 staples only join to very solid base materials, such as wood). Martin's victims, hysterical as they were, could have freed themselves from the T50 staples almost immediately.
Continuity mistake: At the end of the movie, the bloody handprint on the car changes entirely the second time it is shown. (02:02:45)
Continuity mistake: In the opening scene, there are spectators and the camera zooms in on a man and woman with a Rottweiler standing next to the woman. There is a glimpse of two people past the dog. The camera briefly shifts to show a woman (Sonny) walking toward the front door, then returns to the spectators. The Rottweiler (presumably the same dog) is now standing near the left side of a different man (and is not next to the woman). (00:02:02)