Continuity mistake: The "Santa" carrying the Molotov Cocktail walked up the steps and past the decorated handrail, but he was standing within the length of the handrail (about mid-way) when the camera shifted from the right-rear to left-rear side. (00:02:40)
Revealing mistake: The rhino that killed (or "erased") Paul was obviously CGI and quite fake-looking, especially the way it was running. (01:32:50)
Revealing mistake: When William and Jack open the door, enter the room, and walk past the helium-filled balloons (tied to a chair about 4' away), the balloons remain immobile. Due to how light helium balloons are, just opening the door or breathing nearby would be enough to cause the balloons to move somewhat - if they were actually there. (00:16:00)
Continuity mistake: The orange feather toy that was in the cat bed with the cat when Sam got to the bookstore was not there a couple camera shifts later. (00:25:33 - 00:26:25)
Other mistake: Visser was face-to-face with Omar when she shot him in the neck (looked more like it would be in his mouth before the camera shift) yet she did not get any blood splatter on her shooting hand, face, or clothes. There also wasn't much blood on Omar considering he was hit with a near-contact if not actual contact shot. (00:45:41 - 00:47:12)
Revealing mistake: The $100 bills in the briefcase looked quite fake and were obviously a prop. (00:13:40)
Character mistake: Nolan said, "Everybody knows that no sharks swim in freshwater" and Spencer said, "They don't come into freshwater", but there are freshwater sharks (e.g, river sharks) and bull sharks (not true freshwater sharks) can survive in saltwater or freshwater. Jacob Harper (National Aquarium) pointed out eyewitness accounts of sharks swimming up the Mississippi River and "bull sharks have kidneys that recycle salt" but did not mention the glands near their tails that help keep salt in their bodies. (00:08:08 - 00:29:50)
Other mistake: Virgil drives the truck across flat land, yet the dashboard and A/C unit atop it are angled at about 45°. Views of Keith in the passenger seat show a level/horizontal dashboard and A/C unit, like they should be. (00:17:12)
Revealing mistake: The 50 dollar bills that appear in the opening credits all have the same serial number (and you can find online the texture they used with great ease, just like the one for the 20 dollar bills stack). (00:03:45)
Continuity mistake: Before the family went outside, the fire extinguisher was part-way below the window sill. When Peter (father) went inside, the fire extinguisher was away from the window sill (more toward the right of the screen). (00:07:33 - 00:09:12)