Corrected entry: After they drive through the tunnel, they pass through a tollbooth. The sign on the toll says that it accepts the 1 cent coin, more commonly known as the penny. Illinois is the only state in which pennies can be used in tollbooths.
Corrected entry: When Edgar stabs the Arquillians in the neck, they appear to die instantly from their wounds. However we see later at the morgue that the bodies are controlled from a control room in their heads. A neck wound to the robot body would not appear to be fatal to the operator in the robot's head.
Corrected entry: When Tommy Lee Jones and Will Smith are walking through the hallway, right after they're done with the gun test where Smith shoots the little girl, Tommy Lee Jones says "this way" and they turn into the hallway. If you look closely on the right side of the screen, you can see the door that leads to the shooting test, which shows that it's the same hallway that they passed through before.
Corrected entry: When K reveals MIB's existence to J, J replies that K has been reading too many supermarket tabloids. K's response to this is to praise such tabloids as great journalism. These publications reveal information that is, in the film's universe, highly classified. Logically, K would see this as a threat and seek to neuralize, not praise, the staff of these tabloids.
Corrected entry: When "Edgar" walks into the morgue, he's carrying a shotgun. He sets it down by the side of the window. Later, J walks in and starts ringing the bell. You can clearly see there is no shotgun there. Also, when he has the revolver to the lady's head, he doesn't have the gun. So where did the shotgun go?
Corrected entry: In the scene when all the top guys are doing the written test, the guy in the navy blue suit with the combover straightens his test out and it flops back down. If you watch carefully, you can see that he waits for it to flop down.
Corrected entry: In the scene when the alien ship crashes into the truck, it hits it from the side, and therefore would not split it perfectly; instead it would probably cut it in half and the 2 halves would both face diagonally.