Deliberate mistake: After Sam freed Gary from being tied up by the aliens, Gary pulled off the cast he got earlier that day and was able to use his left arm as though it had never been broken. (00:45:43)
Deliberate mistake: After Ryan and Michelle finish changing the flat tire and are surprised by Leatherface, he chases Ryan around the back of the car and smashes the windshield. At the moment the camera is in the backseat shooting out, we see the chainsaw with the chain popped off and hanging. My best guess is that it was done intentionally (for safety reasons) because the saw was close to Ryan. The crew must've been too lazy to completely remove the chain and just popped it off the track instead. (00:25:25)
Deliberate mistake: The video feed from Jill's laptop doesn't match the angle we see her laptop in. The image should be a weird, low-angle shot with lots of space above her head given her laptop is down on her lap, but the image we see is a pristine parallel shot. Additionally, the video footage is way too high quality for a 2013 laptop webcam. (Heck, it's too high quality for a 2024 laptop webcam.)
Deliberate mistake: Otis was portrayed as an albino in "House of 1000 Corpses" but in this film he has normal skin pigment.
Deliberate mistake: When Larry and the two moving men are first bringing the mattress through the doorway and it gets "stuck," the camera placement makes it pretty obvious that the mattress isn't really stuck. There's far too much wiggle room on either end for it to be "stuck." (Obviously it needs to be stuck for the scene to work... but still a weird inconsistency).
Deliberate mistake: This mistake was admitted to in the DVD commentary by the director. When at the embassy, once they open the window, the camera pans up to show a destroyed helicopter on top of the building. This is a mistake as in Moscow, it is restricted airspace for helicopters, with none at all for any purpose to be allowed to fly over the city, not even to land on the American Embassy. However, the director really wanted the visual of a destroyed helicopter on top of the building so added it anyway. (00:41:49)
Deliberate mistake: Blood does - but should not - drain out of deceased Mitch's mouth when he is placed on the couch and his head falls over because Oliver gets up. (00:30:10)
Deliberate mistake: When Kyle goes through the windshield, the windshield shatters like tempered glass. Windshields at the time were made of laminated glass.
Deliberate mistake: Abraham is sitting to the right of and slightly behind the cross he hammered into the ground, but is about 3' away. When there is a close-up, Abraham is much closer to the cross - the end of the crossbar to the right is directly above his shoulder and his knees appear to be close to the vertical bar. (00:45:15)
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.
Deliberate mistake: The oval mirror was in a depressed wall yet was able to reflect a window within the adjacent depressed wall. (00:18:23)
Deliberate mistake: Helena asks Justine over to watch Atonement, but she instead goes on her 'date' with Alexis. When the scene cuts to Helena and Emily watching the film, it's actually The Duchess.
Deliberate mistake: When Chad picks up the cop's gun and fires at Dale and Tucker, the bullets hit the wooden wall. Wood doesn't make ricochet sound. (00:41:45)
Deliberate mistake: There is a wooden chair upside down on the floor, with legs that angle outward. Jack Cain is able to pick up a party-goer, throw him down from over his head, and spear the party-goer on the right side with two of the chair legs. The chair legs are still angled outward but will break off to the side from the force of the party-goer's back hitting them. (01:07:17)
Deliberate mistake: When the cannister rockets through the ceiling window, the pieces of glass from the initial impact never fall down. Nor are they on top of the window in the next shot. They just sort-of vanish. Additionally, the cracks don't match from the first shot to the second time we see it. There's suddenly less cracks which is odd because it's a digital effect.
Deliberate mistake: During his autopsy in Saw IV, it is revealed John Kramer was 52 at the time of his death. Kramer's role in this film is the very early stages of his time as Jigsaw, shortly after his cancer diagnosis, which would put him in his early 50's. However, he looks far too old to convincingly be that young (Tobin Bell was in his mid-70's at the time of filming). He even looks older than he did when he was on his deathbed in Saw III.
Deliberate mistake: Hansel will die if he doesn't take his medicine for 4 hours, but after hanging overnight in a tree he shows no signs of needing.
Deliberate mistake: When Brody confronts and then flees from the Headless Horseman, the horses never break into full gallop (it's little more than a stiff-legged canter), which is odd for a life-and-death chase with the bloodthirsty Headless Horseman in murderous pursuit. This was probably done on purpose, for safety reasons, since the actor playing Brody was performing his own stunt riding at night. To cinch the illusion of a real chase, audio was added of a 4-beat gallop.
Deliberate mistake: In the opening, the kids are looking up at the floor boards. Uniform light seeps through, but as it turns out, the house was small and swarming with an angry mob carrying torch. The light is not really compatible with that scenario, and in fact when the scene is shown later again, the lights are warmer and you can see the torches flickering. It's most likely a trick not to give away exactly what was hunting the kids in the basement. (00:01:00 - 01:11:20)
Deliberate mistake: When the captain jumps towards Scott, the distance between the two rows of seats is three times bigger than the other rows shown, obviously to allow for the fight, but still really weird when you look at it.