Revealing mistake: In the gun battle following the bank robbery, Drucker fires his shotgun at Cherrito. A female pedestrian in the background (apparently unaware she's in the shot) can be seen acting casually, without any reaction to the gun battle taking place.
Revealing mistake: After Nuclear Man destroys the cab's hood, the shot changes and there's a thick string running behind him all along the car.
Revealing mistake: When John, Kate and the Terminator are in the Winnebago, there is a shot that's facing Kate where John says to her that they're going to pull the plug on Skynet and that the bombs won't fall. In this shot, look at John's hair. The green screen is reflected onto it. It is visible throughout the rest of the scene. (01:09:45)
Revealing mistake: Just after Madison says to the Angels, "Looks like one of the three amigos has gone adios" and Drew gets thrown by Madison, Drew hits the wall. For some reason, the camera vibrates.
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 Hulk walks through the stream, the water doesn't react to his feet. (00:59:20)
Revealing mistake: Blank firing adaptors are visible on the bow machine guns of Oddball's Shermans as they shoot up the rail yard. (01:00:05)
Revealing mistake: In one scene, the Penguin is making a "bat" shadow puppet on the ceiling. But there's no light behind his hands. If there's no light, there's no shadow. (01:03:45)
Revealing mistake: Near the end of the film, after the shootout, there's a shot with the camera zooming in on a newspaper at Will Smith's front door. If you pause it right once the headline fills the top of the screen, you'll notice all the paragraphs are just repeated, word for word. Additionally the word "received" is misspelled.
Revealing mistake: Just after Li Mu Bai tells Shu Lien that they are very close to her headquarters and that she should check in, we are treated to two 'time pass' shots of forest. The second of these features some very obvious power or telephone lines in the lower right corner of the screen. (01:22:40)
Revealing mistake: When the Muslim emissary arrives to Jerusalem and Guy de Lusignan stabs him under the chin, look at the blood. It bursts from something attached to his shoulder. In addition, the emissary is seen as stabbed with a small dagger but then Guy De Lusignan is shown holding a full length blood tipped sword a second later.
Revealing mistake: When it shows the video of Tom Cruise on Youtube, on the right side of the screen, the descriptions of the other videos repeat themselves.
Revealing mistake: In the fight between Julie and Ned, when she does the last kick to take him down, it's obvious that she doesn't actually kick him.
Revealing mistake: When Barb is in the bubble bath, you can see the strap from a G-string she is wearing.
Revealing mistake: In the skywalk scene, when McClane pushes the paint stand on the terrorist, it is quite obvious that they use a dummy when the paint stand falls on the terrorist and crushes him. (00:45:05)
Revealing mistake: At the Smithsonian Air and Space Museum, there is a triangular enclosure around Jetfire that amusingly just fades away and vanishes as Jetfire transforms. (01:23:05)
Revealing mistake: When Blackout is destroying the base in Qatar, a few Humvees get flipped over, and none of them have engines in them. (00:07:00)
Revealing mistake: In the New York meteor shower scene, most of the cars blow up without having been hit at all.
Revealing mistake: When the sheriff's car is flipped upside down, the sign behind the car is upside down too, so you can tell the car isn't really upside down.
Revealing mistake: When Montoya uses a spear to toss the vampire woman from the prison door into the sunlit street, it is an obvious dummy that has been used. First you see the woman stumble out, and the first flames shoot out of her, then the angle changes to a close-up of her as she is engulfed in fire. In the close-up, she has become bigger and rounder, and does not move.