Revealing mistake: Near the end, as they approach LAX, the woman says there is nobody on the ground, that it's just the same as Bangor, but actually you can see a few cars moving on the ground.
Revealing mistake: In one of the final scenes where Stallone is hanging out of the Statue of Liberty, you can see that his "JUSTICE TATTOO" on his upper arm is a fake. You can see at the edge of the tattoo that it is glued on the skin.
Revealing mistake: When the Rangers kick Oozemen's ass, the pink Ranger starts off with the "You guys make me sick sick sick -kick". While all Rangers are fighting, the blue one is just standing still next to the camera. You can see his shoe in the in the lower right corner waiting for his entrance. (00:22:30)
Revealing mistake: In most of the underwater shots you can see bubbles coming up from the cameraman.
Revealing mistake: When Sil fakes her death, the breaker box explodes before the car hits it.
Revealing mistake: When Dr. Railly is tied to the bed in the motel, her bonds are not very secure. In her struggles, she very nearly frees her right foot, by accident.
Revealing mistake: When everyone jumps from the plane, all of the stunt doubles are easily seen - [Dr. Elliot's stunt double is ridiculously easy to spot!] (00:37:00)
Revealing mistake: In the scene where Sid has had his hand blown to pieces, and he is running, you can see that that arm is longer than the other, that the damaged hand has been attached to Russel's arm.
Revealing mistake: In the beginning when Keanu Reeves goes to a ruined building in the ghetto to get the info inside his head extracted (at least that's what he expects) he comes across a couple of bad guys. Watch closely though as he hits the black guy, and you'll see that he actually doesn't hit him at all.
Revealing mistake: When the eye doctor becomes hypnotized to put the wrong drops in her own eyes, if you watch the bottle nothing ever comes out of it that could cause her to scream.
Revealing mistake: When Dwight is falling down the stairs, you can easily tell that it's a (much older) stuntman.
Revealing mistake: After stealing the battery out of Durant's weapon near the end, as Westlake says "Batteries not included", you can see the actor's undamaged lips under the fake burn prosthetics on his face and mouth. (Look underneath the exposed teeth where his lips supposedly were burned off.).