Revealing mistake: Each crew member has a monitor on their spacesuits that they use whenever they are exploring the caves. Whenever the monitor is shown, each crew member's individual heartbeat is shown in the lower left corner of the monitor. But no matter which heartbeat is shown, every time a heartbeat on the monitors is shown, it is always the exact same heartbeat, despite the various changes in panic and stress throughout the movie.
Revealing mistake: You can see the blue screens on Bruce Banner's glasses when Tony Stark is talking to him about embracing the Hulk rather than disliking it. (00:57:40)
Revealing mistake: At Coney Island, K zaps J's neck with a tazer and knocks him out. J is seen falling onto his back on the ground, where the background fades out to show time passage that he wakes up sitting in a chair in MiB head quarters. The effect was cool, but the way it was done reveals itself. J wakes up in a leaning back seated position looking up as his head is slumped back over the chair. It is obvious they used this part of the footage to show him lying flat on his back on the ground at Coney Island, only you can tell he is not lying flat on his back. (00:42:55)
Revealing mistake: When Katniss is blown back from the explosion, her stunt person is visible. This can be proven because the stuntperson's skin tone is different and her hair is not in a braid. It is in a ponytail. Wires can also be seen pulling her to give the illusion that she was blown back from the explosion. (01:33:00)
Revealing mistake: When Sparky's tail pops off there is a hole where it popped off. But when the tail goes into the bucket the hole is gone.
Revealing mistake: When Dredd throws Kay onto the table, Kay is supposedly handcuffed, but his hands spread apart way further than they should have.
Revealing mistake: When Alice shoots the zombie in the blue dress, we get a frontal shot of the gun. Pay close attention to her trigger finger: it doesn't move at all, while the gun does fire.
Revealing mistake: When the three characters are playing with legos and Matt is told to start playing music from his ipod, you can see that the sound is off and the ipod is paused when the music is apparently playing.
Revealing mistake: Considerable efforts were made for this film to have Joseph Gordon-Levitt resemble Bruce Willis (colored contacts, nose prosthetics) since they are playing the same character at different ages. Yet the two actors' ears remain distinctly different. Bruce Willis's ears are much larger than Joseph Gordon-Levitt's, and Joseph Gordon-Levitt has connected ear lobes while Bruce Willis does not.
Revealing mistake: In the scene when Dodge is knocking at the second house to see if Olivia is home, check out the top left corner of the screen during the shot of Penny sitting in the car - a bird flies by inside the car. The only reasonable explanation is that the visual effects team not only made the bird graphic visible through the window but also in front of the rest of the car. They might have forgotten to bring the car layer in front of the bird layer, causing a bird to be seen flying over top of the entire image. (01:14:00)
Suggested correction: It's a reflection in the windshield.