Revealing mistake: When Asher is shooting a bolt-action sniper rifle there's no casing ejecting from the rifle as he reloads it with the bolt. (00:48:30 - 00:49:25)
Revealing mistake: While they're finally on the rapids, the girl blindfold keeps changing position from her neck to her forehead. (01:40:59)
Revealing mistake: Near the end when the orphans are exiting the building in the bus, you can tell they practised the sliding part. There are marks in the roof of the bus from previous takes.
Revealing mistake: Vera types "Nico Lasarte - Murdered - 1989" into a web browser. When she clicks the search button and the screen changes to list the search results, Vera's position in the frame can be seen shifting on-screen, revealing that the shot of the search bar and the shot of the search results were two separate shots merged together. (00:57:20)
Revealing mistake: When Scott is fighting Ghost, as Pym is planning to dive, Ghost throws Scott through a wall and you can see the braking cable around his/the stuntman's waist and across the floor. (01:16:48)
Revealing mistake: Normally I wouldn't consider a bad CGI effect to be a mistake, but when Elise finds the hidden keyhole in the wall in the basement, the effect is comical if you pay attention. The way it appears as she scratches is pretty unnatural, and the pieces of paint that fall practically look like cartoon pieces if you pay attention. The shadow of her left hand also looks a little too sharp compared to the rest of her (somewhat softer) shadow, revealing it was likely rotoscopped in some way.
Revealing mistake: Eve says they need to make sure nobody gets shot, so she picks up Franklin's pistol and takes out the magazine to store them separately. However in this shot the magazine is completely empty with no bullets anyway. (00:53:40)
Revealing mistake: When Bearman and the President are running from the Russians, we see some Russian 4x4's doing a hard turn to chase them. In this shot you can see skid marks from previous takes. (01:15:30)
Revealing mistake: Margaret's car and the way it was situated relative to already-parked cars in the courthouse lot was awkward. When she was sitting in the car, the driver's side-view mirror was angled outward yet gave a clear reflection of her face. The car in the row behind her was too close and at an angle, which would have likely blocked her approach. The car to her left was angled like a "V" to her car. These suggest/ indicate a green screen was used. Margaret's car appeared to be parked in the through lane. (00:53:58 - 00:56:52)
Revealing mistake: In the beginning when they're having shots at Hellfest, the guy with the gray shirt holding syringe shots has a stain directly in the middle of his shirt between the drawstrings, 5 seconds later it's gone. (00:13:32 - 00:14:03)
Revealing mistake: When Bu is packing up his things in his bedroom, the camera appears to sway abruptly from side to side two or three times during the scene, almost as if the cameraman couldn't keep the camera steady. (00:57:25 - 00:57:50)
Revealing mistake: After Mel is killed, Scott drives away in a truck that they were just hiding behind during the shoot out. But there is not a single bullet hole or sign of damage to the truck.
Revealing mistake: When Brother Swan goes to blow on the "horn" (which is actually an ocarina), he toots out a few different notes. However his fingers stay completely stationary on the instrument and not moving around on the holes to change the notes. So it would have been just one sound but it plays like 3. (00:29:25)
Revealing mistake: When Velma sabotages the science project making it explode into purple goo, you can see that the vial of chemicals she tampered with simply spray around clean liquid, and the purple goo falls from above. (00:23:55)