Revealing mistake: The very first shot of the movie, supposedly of Anya Taylor-Joy lighting a cigarette, does not match the following shot on the pier; the cigarette appears to be black and with a brand sleeve instead of the normal one she is smoking. The background confusingly looks more like an interior than the pier she is standing on, and the lighter is a common Bic-style one instead of the Zippo she is using also later in the movie. That's because it's actually stock footage. You can literally find the clip yourself on Shutterstock and similar websites, by the description "Close-up of the silhouette of a woman's face sticking a cigarette into her lips, igniting her with a lighter, and exhaling smoke. The grim concept of the harm of smoking in a low key." (00:01:00)
Revealing mistake: In the underwater view of the fish, the ice hole is almost perfectly round and the ice appears to be quite thin - nowhere near the several inches Jason and Ben have to chip away to reach water. (00:33:55)
Revealing mistake: Christine closed her dead brother's eyes without actually touching them. Christine had an open hand (no cupped palm) with her fingers straight out and together; her pinkie finger touched her brother's nose, meaning her other fingers would have been too far away from his eyes and unable to make contact. (01:11:03)
Revealing mistake: When Danny follows Maria outside, he is in front of a well-lighted wide patio door with side windows and there are numerous decorative lights to his right. Thereafter, close-up views of him talking show only some small red lights to his right; the rest of the screen is black. Wide views continue showing the lit entryway behind him. (00:08:44)
Revealing mistake: A dog would not be able to jump through a vehicle's window and land on shattered glass covering the rear seat without getting its paw pads cut. The shattered "glass" that Lulu was standing and sliding on appeared to be ice. (01:07:29)
Revealing mistake: The views to the right and left of the truck on the road did not flow in the manner expected if they were actually there (as opposed to using a green screen). Also, as soon as a "stop" sign could be seen to the right, the camera shifted to the driver, who kept driving as though the stop sign was not there. The structures to the right of the truck were blue but became white when the camera shifted to a front view (not using a green screen). (00:01:20)
Revealing mistake: During the scene with the ships hanging from the helicopters, Nate decides to fire a cannonball at the other helicopter as it's coming towards them. A standard cannonball shot from a 36 pound cannon that the Spanish used on their ships weighs 16.5 kilograms (the weight of a large full water dispenser bottle) but Nate tosses it around like it weighs nothing.
Revealing mistake: Robert's upper body is leaning against a pillow with his adjustable bed at about a 60° angle, and stays at this angle when there are front views of him. After Paul arrives, views of Paul that include only part of Robert's stomach/torso show Robert lying at a lower angle, closer to 45°. Sometimes, the blanket representing where Robert's stomach would be is all that is included. Robert [Bruce Willis] probably was not present when front views of Paul were filmed. (00:25:09 - 00:25:33)
Revealing mistake: When the boulder rolling down the hill hit the man, he "vanished" - he was not flung into the air and it did not look like he got run over by the boulder. [Poor/ineffective CGI]. (00:31:55)
Revealing mistake: Max rolled down the front passenger side window and no wind came into the car, but when he had his face barely out the window, his hat blew off (not shown on screen). If wind hit the visor part of his "bugout" hat, the hat would have most likely blown off into the car. (00:03:40)
Revealing mistake: Initially, there is a little movement that can be seen in the passenger's side mirror on Juan's car, but it is subsequently reduced to still-frame. Also, the driver's side mirror is tilted upward, showing movement, but not in a typical position to enable viewing of vehicles behind the driver. (00:00:55)
Revealing mistake: This happens in the second ceremony when Wolf didn't press the button to shut off the lights to steal the golden dolphin because of the good comments. Few seconds later, the lights shut off, and you can see that the meteor on the top disappears at the time.
Revealing mistake: At the hangar junkyard, there were a few 5-gallon gas containers around several "flammable" barrels that The Thief shot at in order to ignite/cause an explosion near Temple's goons. The huge explosion engulfed the whole area, but seconds later it could be seen that the flames were confined behind or within the circle of barrels and the gas cans were not affected. (01:13:10)
Revealing mistake: While with Abigail, doors open to reveal a city and a plane behind which rises big jets of air that move Loretta's hair. However, the decorations on the table don't move a single inch (until several shots later), giving away that the city behind is CGI.
Revealing mistake: When Chris Evans is dragging the girl into the maze at the end you can see the burn mark on his shoulder creasing with his shirt.
Revealing mistake: During the (second) bank robbery, the ceiling was frequently unusually close to the top of the robbers' heads (inadequate clearance), indicative of a poorly positioned green screen (or CGI). (00:16:35 - 00:17:00)
Revealing mistake: There's something odd about the chair that is (or is not?) to the right of Monsignor Kelly when Stu goes into his office to talk. Only part of the back of the chair can be seen and it is not directly in front of the Monsignor, but there is not enough room for the seat part to be there (otherwise, the Monsignor could not be standing where he is). Without any indication that the Monsignor or chair moved, the Monsignor is later able to rest his right hand on the chair's back. (01:13:57 - 01:14:37)
Revealing mistake: After the shark got Lisa, Annie climbed atop her overturned kayak and was lying with her stomach about mid-way on the kayak with her feet over the back sides. The kayak was not long enough for Annie to have her body on half of it; her legs did not look real (odd-shaped and disproportionately short/CGI). When Nic got to the kayak, Annie's toes were on top of the (overturned) kayak instead of her feet hanging over the sides. (00:36:21)
Revealing mistake: It was quite obvious that the beaver was fake, and not a very good one relative to the capabilities of contemporary CGI. (The first time, the beaver was presented as real; the second time, it was meant to be comical). (00:59:20 - 01:29:13)
Revealing mistake: In the wide view, the tree trunk is perpendicular to the level ground while Birdy and her cousin are standing. There is no large tree to the left, just a fence-like display of shrubbery parallel to the ground running across the rear of the screen. When the camera shifts to the girls sitting next to the trunk, they are made to appear as though they are sitting on a grade (not level ground), the background shrubbery runs diagonally across the screen, and a large tree is visible to the left. (00:32:38)