Factual error: The amount of blood that comes out of the main characters hand when his fingers are cut off is too much to be realistic at all.
Continuity mistake: In the scene where Paxton runs over the three Slovakian scammers with his car. Just when he hits them, you can see for a split second that the dark haired girl in the middle smashes on the windshield and "sticks" on it. But in the next shot she can be seen rolling over the car. (Slow-motion is not needed to see this.)
Revealing mistake: When the businessman has his fingers cut off by the lead character, you can tell the hand is a prop, as the skin tone does not match his hand in previous shots, and it moves unrealistically.
Continuity mistake: When the main character is being threatened by the man with the chainsaw, in one shot the chainsaw is being held near his face at about his mouth-level, but in the next shot, it is suddenly about 4-6 inches higher, right in front of his eyes.
Continuity mistake: During the first scene at the disco, closely watch the two Asian girls. Right at the beginning of the scene, they are off to the right, dancing about a yard apart. Immediately in the next shot, they are standing right beside each other.
Continuity mistake: When Paxton follows the Dutch businessman down the stairs into the station, he passes a girl with jeans, crop top/jacket and carrying a white bag who is beginning to go down the stairs. When the angle switches (looking up the stairs at Paxton coming down) the same girl passes him going up the stairs.
Revealing mistake: When the kids throw rocks at the bad guys, there is blood on his head before he is hit.
Factual error: At the red light district, the windows are not lit up red. They're rather lit up blue, meaning these would be all transgender/transvestites.
Plot hole: When Paxton runs to the changing room, he does so at the same time the two employees are turning, meaning they should have seen him. He also shuts the door to the room after they have turned and are walking straight. In addition he was covered in blood and left bloody footprints, therefore they should have caught him and immediately recognized him as an escapee.
Continuity mistake: Right before the businessman has his throat slashed, this is a smear of blood on his right shoulder. After his throat is slashed, the smear disappears.
Continuity mistake: This is a hard one to spot. The businessman's glasses slightly change position at least once without him moving them when he is being killed. The line of the bathroom tile is near where the right lens holder and lens meet, but after he has been killed, the tile line is now in the middle of the lens.
Continuity mistake: When the German torturer holds the chainsaw to Paxton, we are shown a shot of Paxton's shoes and they already appear to be wet from vomit before he does so.
Deliberate mistake: The chainsaw cuts off the German torturer's leg and it manages to move all by itself a few feet within a few seconds, when it would just run and slowly move and stall as seen after it moves. Obviously done to increase the tension. In addition, the chainsaw looks very clean with no blood dripping and bloodstains on the floor.
Continuity mistake: When the German torturer goes to get the chainsaw, he drops the gun on top of a machete that is on the edge of the table. When the table is shown when Paxton is escaping, there is no machete on the table. It also appears that the gun moves closer to the three blades which are in the middle of the table.
Continuity mistake: We see a bloody hole on Josh's face which is obviously not made by the drill. This is in fact because part of the scene was cut where the torturer poked him in the face with a metallic object. Since no versions of that scene exist, it makes no sense for it to be there.
Continuity mistake: The torturer crawls to get the chainsaw and as Paxton goes to shoot him he's sitting up.
Continuity mistake: While they're on the train from Amsterdam after Alex tells them where to go for the women if you look out of the window and watch the countryside you see the same road and tree at least three times.
Answer: I'll have to re-watch to catch the bad-guy's words, but Paxton keeps saying, please don't take my life, I haven't done anything.