Best sci-fi movie revealing mistakes of all time

Please vote as you browse around to help the best rise to the top.

Predator picture

Revealing mistake: Mac and Dillon go after the Predator. The Predator is sitting in a tree, and Mac points him out to Dillon. They both agree that they see it and take position. Mac crawls underneath the alien and is killed by his laser. The Predator then sees Dillon and lasers his arm off. Dillon's arm falls to the ground with the gun firing. Quickly Dillon turns and reaches for the machine gun around his neck. When he turns you clearly see his bloody right stump and his right arm sticking out the bottom of his jacket. [Note: As far as I can work out, this has been cunningly edited out of the UK DVD version].

More Predator revealing mistakes
Teenage Mutant Ninja Turtles picture

Revealing mistake: When three of the turtles are playing Trivial Pursuit and Leonardo runs in to announce Splinter is alive, you can see a wire coming out of Raphael's shell. I guess it's for the animatronic head, but it's visible. (00:59:30)

More Teenage Mutant Ninja Turtles revealing mistakes
The Core picture

Revealing mistake: In the Trafalgar Square scene when the double decker bus flips onto its side there is a shot of it from the front, and it has no engine or radiator. (00:08:10)

Upvote valid corrections to help move entries into the corrections section.

Suggested correction: Some buses in the Uk have their engines and radiators in the back of the bus.

Not that one. Sorry to expose my inner geek but that is a 1961 AEC/Leyland Routemaster bus and the engine and radiator were mounted in the front.

More The Core revealing mistakes
Ghostbusters picture

Revealing mistake: There's a scene where Dana's building is falling apart and stones and stuff are falling to the street below. One of the huge boulders bounces off a wooden police barricade in the bottom left hand corner of the screen, and then off a person. (01:29:14)

More Ghostbusters revealing mistakes
The Fifth Element picture The Fifth Element mistake picture

Revealing mistake: Right after they "create" Leeloo and she is lying in the plastic cage with the little straps on her, the guy approaches her and says, "if you want out, you are going to have to work on your communication skills." She gives him a dirty look, and then you can see a huge hole, pre-cut in the glass, that she busts her hand through. (00:29:47)

More The Fifth Element revealing mistakes
Star Trek V: The Final Frontier picture

Revealing mistake: The graphic display showing the Enterprise lowering shields is actually just a repeat of the earlier display showing the vessel raising her shields...played backwards. The giveaway is the screen still reads "Activating Deflector Shields" even though Scotty is supposed to be dropping them.

More Star Trek V: The Final Frontier revealing mistakes
Superman II picture

Revealing mistake: There are two times in the New York battle when you can see the actors are being filmed in front of a screen: 1. when Superman kicks Non, Superman in on film and Non is hovering in front of the screen. 2. When Ursa is flying towards Non and Superman with the flagpole, she is hovering in front of the screen.

More Superman II revealing mistakes
More Terminator Salvation revealing mistakes
Sharknado picture

Revealing mistake: When Fin decides to help the kids on the bus and says, "Water's rising, I'm gonna go up to the bridge and rappel down," two shots later the camera zooms in on Fin's car up on the bridge, but the problem is that this shot is shown in reverse - all the vehicles in both lanes are going backwards.

Super Grover

More Sharknado revealing mistakes
Short Circuit picture

Revealing mistake: When Number 5 is leading Number 3 into the toilet and moves at the last minute, you see Number 5 falling over, but in the next scene, he's perfectly fine.

More Short Circuit revealing mistakes
The Matrix Revolutions picture

Revealing mistake: In the scene where Captain Mifune is defending a bridge, alone, and commands "reload", he put the right arm of the APU straight, revealing in the background some sparks that floats independent of the action and stops for a few moments.

More The Matrix Revolutions revealing mistakes
2001: A Space Odyssey picture

Revealing mistake: When we see the space station from the cockpit of the approaching shuttle, the station does not appear to rotate because the shuttle is rotating at the same speed. OK...except that the station IS still rotating with respect to the sun, which means that the light source and shadows on the station should be moving.

More 2001: A Space Odyssey revealing mistakes
The Fly picture

Revealing mistake: In the scene where Ronnie visits Brundlefly for the second time we see Brundlefly walking on the ceiling and wall, however his shirt doesn't remain consistent with gravity. This is especially obvious when he pulls his shirt up to show Ronnie his new tumor and then places it back down. The shirt appears to be being pulled up to towards the sky from Ronnie's perspective. (01:07:30)

Matt Rengers

More The Fly revealing mistakes
Starship Troopers picture Starship Troopers mistake picture

Revealing mistake: When they are learning how to throw knives, the guy gets one thrown through his hand. If you watch this carefully, blood starts coming out of his hand before the knife hits. (00:28:45)

More Starship Troopers revealing mistakes
Star Trek: Insurrection picture

Revealing mistake: In the beginning scene on the Bak'u planet the stone bridge bends under the weight of the child. (00:04:15)

More Star Trek: Insurrection revealing mistakes
More Superman IV: The Quest for Peace revealing mistakes
Forbidden Planet picture

Revealing mistake: Halfway through the movie, Alta is swimming in the pond, supposedly nude. However, when she climbs out, she can be seen wearing a flesh-covered swimsuit. (00:45:15)

Westing1992

Upvote valid corrections to help move entries into the corrections section.

Suggested correction: Alta never said she was naked. She didn't know what a bathing suit was and Adams assumed she was naked.

More Forbidden Planet revealing mistakes
Terminator 3: Rise of the Machines picture

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)

THGhost

More Terminator 3: Rise of the Machines revealing mistakes
Judge Dredd picture

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.

More Judge Dredd revealing mistakes
The Incredible Hulk picture

Revealing mistake: When the Hulk walks through the stream, the water doesn't react to his feet. (00:59:20)

More The Incredible Hulk revealing mistakes