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: A flare thrown on top of a snow-covered mound of logs/twigs is not able to engulf the area as fast as it does. (01:13:13)
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 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: When Ami's school friend is killed, a short sword is stabbed into the top of her head. Less than a half-second later, we see her face is totally coated in blood, and she gurgles even more blood before dying. There simply has not been enough time for such a volume of blood to have dripped down her face.
Deliberate mistake: The surviving passengers are all awoken from a deep sleep after Dinah realises the other passengers have gone. Yet none of them appear drowsy or tired and none of their eyes appear strained, despite having just woken up so suddenly. (00:09:20)
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: 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.
Suggested correction: It does make sense. The wheelchair wasn't secured and contained lots of metal, so it was immediately pulled towards the scanner. The screwdriver had a lot less metal, and Trew was holding it very tightly, and she knew what was about to happen, so she should strengthen her grip even more, allowing her to keep hold of it.
Preposterous. Depending on how they're set, MRI magnets can yank entire hospital beds clear across the room, and even once killed a man by setting off a concealed gun he was carrying. There's no way she was holding onto that thing.
Deliberate mistake: In the dark, dilapidated house, Margaret asked Abby, "What's that?" and Abby was able to illuminate a large portion of the room with a disposable lighter. (00:16:35)
Deliberate mistake: The snacks in the vending machine were almost to the top of each display shelf, but an interior to exterior view showed the lab researcher's head unobstructed and a foot or so clearance between the snacks and the top of the shelf. (00:06:30)
Deliberate mistake: When Kasady and his symbiote are fighting for control at the bell tower, they are reflected inside Venom's eyes...who is lying on his back in the middle of the cathedral and is nowhere near and at the totally wrong angle for a reflection like that to happen. (01:15:50)
Deliberate mistake: When Dead Reckoning is firing the missiles at the end (towards the crowd that's being eaten by zombies), you can tell that they repeat the same shot of the missile firing three separate times, even though it's supposed to be three different missiles. (It's the shot of the exhaust coming out of the back of the launcher.) They try to mask it by cutting a little earlier or later each time... but it's obvious.
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: Candy tells her radio listeners, "Our phone number is 201-5137." Assuming the radio station's reception extends beyond more than a small geographic area, an area code is needed for callers outside of the immediate area. On Ellie's cell phone, Mary's number shows up with an area code. (00:05:55 - 00:07:20)
Deliberate mistake: The Janitor was driving away from Willy's but the explosion shows up in the front of his sunglasses. (01:21:47)
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)
Deliberate mistake: When they're watching the footage of the tsunami hitting Cannon Beach, Sabrina turns the TV off as the shot pulls backwards. Suddenly, the glare on the TV appears out of nowhere.
Deliberate mistake: The disco ball doesn't start reflecting the sunrise until after the lead characters get out, even though it should have began to reflect light right when the door opened.
Deliberate mistake: In the whole of the 'Psycho' series, there has never been a closet door next to the dress cabinet in Mother's room, but for this movie there is suddenly a closet.
Deliberate mistake: When Violator turns back into Clown in the alley, watch closely. You can see his shadow beneath him for a few seconds as he's transforming, and it doesn't match the transformation of the giant monster into the Clown... it's just Clown's regular shadow from the actor standing on-set. More than likely, it's a shortcut for the effects - they didn't bother rendering a simulated shadow. You have to look kinda close to notice it the first time, but once you see it, it's obvious.