Plot hole: The killer has been living in the (apparently big enough) crawlspace between walls and floors, for over a decade. There is no explanation (or rationale) given on how he moved the various objects inside every room, closed doors, fed when the house was not occupied, hid the various corpses and, silly detail, concealed his own BO and the stench of his own living quarters, which is something hinted at when they find out his hideout. It is explicitly said that he is agoraphobic and does not get out, ever.
Other mistake: Aladdin slices off one head of the monster in the tomb. The body spurts copious amounts of blood and the severed head even bounces on him repeatedly, but Aladdin's shirt is immaculate afterwards. (00:04:40)
Continuity mistake: Throughout the film, John Travolta's hair changes back and forth and back and forth from being really really really short to just really short.
Continuity mistake: When the guy with the hat plays pool and goes to hit the blue ball, in the next shot it changes to white and he completely miscues. (00:27:25)
Continuity mistake: In the intro, the mother is playing with her kid; notice that when she grabs the gladiator puppet she is holding it with the index finger above the shoulder in the wider angle, below in the frontal close-up. (00:01:00)
Continuity mistake: When Eddie Murphy's assistant makes assumptions about why Jack isn't speaking, he throws his notepad down and has empty hands as Jack pushes him out of the office. When the angle changes, he has a notepad in his right hand.
Continuity mistake: When the form falls onto the girl's face, the position of the form changes between shots. (00:00:35)
Revealing mistake: When Three Finger is driving the truck to ram the car containing Angela's husband you can see round the eyes that it is a mask being worn.
Visible crew/equipment: When the 2 bad guys get the car you can see the 2 cameramen reflected in the car door. (01:10:00)
Factual error: The movie changes between a basketball season and a playoff basketball game then to a baseball game being played in what looks like early summer...back to a team getting ready for the basketball playoffs. The two seasons don't overlap.
Continuity mistake: When the dog comes in and takes Dale's hand the blonde woman's legs keep changing position. (00:47:00)
Other mistake: During the end credits, there's a misspelling. An 's' is missing from 'First Assitant Camera'. (01:33:05)
Continuity mistake: Wren is asking her mother about the form for the college loan. When she remarks sarcastically "Afghan citizenship, hello?" she has a big bunch of hair in front of her shoulder, as opposed to the previous shot. (00:02:30)
Factual error: The Iowa is sailing with a depleted crew, one that most likely has no experienced gunner's mates. The 16-inch turret requires a 79-man crew to operate it, and can fire a salvo every 30 seconds. Despite these handicaps, the minimal crew in the movie was firing salvos every few seconds.
Continuity mistake: George's son is disappointed because his dad missed the ball game and tells him that he should have been there. Meanwhile Denise Richards approaches the cooking pot with her spoon in her right hand and the plate in her left. Close-up on her telling Howie that dad was busy, and spoon and plate switched hands. (00:18:45)
Continuity mistake: The German and British airmen are looking at the Northern lights. From the rear the men are apart, but the front shots of them show them much closer to each other.
Continuity mistake: When Sheriff Cooper writes "Karsson" and underlines it on the chalkboard, the way it is written changes between shots. In one particular shot, the line he underlined it with is suddenly rubbed out.
Other mistake: After the medical student leaves the unconscious co-pilot to one of the other passengers to watch while he goes to the bathroom, she notices his hands grow cold after a bit. It is only then they realise he has stopped breathing, and then get a defibrillator out and are successfully able to use it to revive him with CPR as well. However if he has stopped breathing for long enough that his hands have started to get cold, he would already be way too far gone to be able to be revived.
Continuity mistake: In the parking garage scene, when Lindsay initially parks the sign states "Reserved For Walter Deeds." When being towed his name on the sign disappears. (00:06:30 - 00:10:45)
Continuity mistake: When the mean Santa puts the little girl in his lap and asks her what she wants, she's wearing gloves. When it cuts to a different angle, suddenly her gloves are gone.