Revealing mistake: When Loomis shoots the marshal's window out, when he makes a u-turn you can see the tire marks on the road and dirt from previous takes.
Plot hole: Patrick Redfern needs someone to be in the boat with him to corroborate his and his wife's deception and be his alibi. That is whole point of his wife lying on beach - he gets this when taking Myra for a ride - but it was portrayed as a random ride she got, he did not intend or plan giving her a ride, he did not see her loitering near the boat, or even in view of him untying the boat. Even if that was intention in the story for him to be seen ready to cast off, the movie viewers did not see her viewing him, only her appearing just before he was set to cast off. Without someone with him the whole deception would not work, he would have no alibi, he could have killed Arlena unseen.
Plot hole: Shortly after the robbery, Kevin Kline and Jamie Lee Curtis get together in a little flat and Kline calls the police from a landline to tell them who committed the robbery. In England this would immediately lead the police to the flat from which the call was made, and the person reporting the robbery would be the first person the police would want to find and speak to. Otto has handed it to them on a plate. (00:12:29)
Plot hole: Peter goes into Carl's mind to save Catherine. When he's in there he sees the tank with the water nymph. On the tank are strange symbols which provide the FBI with the clue needed to find the latest victim. Makes sense so far. But, go back to the scene just after the FBI have captured the comatose killer and are looking in his basement. The FBI are looking at the contraption that the killer uses to suspend himself over the victim. On the contraption is the same symbol seen later on the water nymph's tank. Why didn't the FBI follow up the symbol then?
Other mistake: During his conversation with the landlord of the pub he ends up staying in, Sergeant Howie makes it clear that he did not intend to stay on Summerisle overnight, that he had been delayed and so needed accommodation. Makes you wonder why he packed his pyjamas. He's wearing them when Britt Ecklund does her famous naked song and dance routine, and they are not new so we know he didn't buy them that day. When he arrived he didn't even think he'd be on Summerisle for more than a few hours - we don't see him with so much as an overnight bag.
Plot hole: The entire plot hinges on the villain's gang obtaining the tablet that allows admin access to the building's systems. However, it can only be unlocked via facial recognition and it is keyed only to Will Sawyer's face. In fact, when they finally do get it, Xia unlocks it by holding it up to Sawyer's face. So what was the point of trying to steal the backpack containing the tablet? Without Will to unlock it, the tablet is useless.
Visible crew/equipment: When Officer Romero and Arthur are alone in the house, handcuffed to the brass shelving unit, as she says, "Help me or I will crush you like a damn bug," a crewmember wearing glasses and a blue shirt is seen crouching on the floor, at the bottom right of the screen. (00:53:05)
Continuity mistake: During the chase scene on the bridge involving the tank, two cars (silver Toyota Corolla hatchback, licence NE34 12 and a black VW Bora, licence NU67 67) appear during many shots, often travelling in different directions on the bridge and either ahead or behind the chase.
Continuity mistake: In the wide-angle shots of the blue Willys (Jeep) wagon, the windshield is a 2-piece version with a vertical divider in the middle. The close-up shots don't have the divider.
Other mistake: In the pre-credit scenes when the chopper spots the runaway car, Driver guns it (he clenches his jaw, fists and you hear the engine revving and gears changing) but he never catches up with the two cars only a few feet in front of him (which are proceeding at normal speed) for the whole length of the bridge.
Revealing mistake: In the disco scene, the DJ is playing music, but the Pioneer decks and the DJ Mixer are not even turned on, as no lights are showing.
Factual error: At the beginning, the film is set in 1995 only for a brief few minutes. Then, it goes on to say "15 years later." This brings us to 2010. In 2010, the latest iPhone was the 4. However, throughout this film, nearly every iPhone shown (quite a few) appears to be an iPhone 5s. This is obvious by the rectangular body with fingerprint sensor. In addition, in some places the latest iPads are used, the iPad Air 2 and the iPad mini 3 - These were released in 2013 and beyond. Finally, although I am not 100% sure, towards the end of the film as the woman steps in to the car for the final time on the hill next to the boat, it appears she is wearing a gold Apple Watch or other smart-watch which was released later than 2010.
Revealing mistake: Riggs handcuffs himself to the depressed businessman. They jump off the building but they're not handcuffed to each other anymore. They used plastic cuffs which could separate during the stunt in case anything went wrong. They break just as they jump, so they grab each other's hands to stay in contact. After they land the cuffs are attached again. (00:31:00)