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: 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: The photographs that Angela takes off the boys that show the girls naked obviously were not taken outside the cabin, they are far too clear. The fly netting and window would have obscured them. Also, judging by the position of the beds in the photographs it seems like they were taken inside the cabin. (00:32:02)
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 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: When Tree turns on the magnetic medical equipment, it's somehow strong enough to yank a big, heavy wheelchair up and pin Gregory in only a split-second, but not strong enough to instantly pull the screwdriver out of Tree's hand? Obviously this was done so Tree could have a cool moment where she lets go of the screwdriver and it impales Gregory... but it makes no real sense.
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: 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: After trying to get away from the monster, Costello finally unties the boat as Abbott rows away from the burning dock. The next shot of the boat has Abbott slowly rowing the boat, but you can see it's not moving as there's no wake, and when they jump off the boat after the Invisible man speaks, it doesn't rock, meaning the boat was mounted to something to prevent any movement, so they could make the jumps into the water.
Deliberate mistake: The wrecker used in this film is a Western Star Model 4964. The manufacturer emblem (a chrome 5-point star superimposed on a large "W") is normally displayed at the top-center of the truck's radiator. Apparently, the film makers could not bring Western Star on board for an advertising agreement, or Western Star specifically objected to their logo appearing in the movie, because the Western Star emblem on the wrecker's radiator is carefully kept out of frame or otherwise obstructed from view throughout the film. For scenes in which a full frontal shot of the wrecker is unavoidable, the Western Star emblem is very deliberately covered up with dark green tape.
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 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.
Deliberate mistake: The images of Spencer's face in the driver's side mirror are not realistic for someone in the driver's seat. The driver's side mirror is angled outward (perhaps 60° beyond a typical angle), but his face is perfectly reflected. When Spencer starts smoking, the viewer gets a glimpse of a figure behind his car. Spencer senses something and his face is shown backwards in the mirror, as if he were crouching outside a few feet from his car. Spencer does not use the more practical rearview mirror. (00:19:11 - 00:19:47)
Deliberate mistake: The number of clicks (sounds) Christine made on the "text to talk" device did not match the total characters she typed. With few exceptions, there were a lot less clicks/sounds than there should have been based on the amount of letters/words she typed. (00:06:40 - 00:15:30)
Deliberate mistake: The blades on the tiller or harrow (?) were only a few inches apart when Burkett was falling back onto them, but only one blade went through his chest. Burkett's body was wide enough for at least three blades to penetrate. Also, the blade appeared to be exiting in the center of his chest (along the button line of his shirt), but the close-up showed the blade to his right. (00:19:40)