Deliberate "mistake": When MIB agents exit the lift to get into the main hall of the MIB Office, the lift opens halfway up the wall and they need to go down a little platform. But when K and J return during the lockdown and face the trashcan with guns, the lift opens at floor level, so it can be conveniently peppered with bullets.

Continuity: When Frank the dog is growling at the agent in the park his teeth are fine but later talking to Zed he is told he can have better dental. He smiles and his teeth are horrible.

Visible crew/equipment: When agent Kay is in the elevator with the little worm dudes he swings down and starts shooting at the robot. When he swings down you can see the safety harness between his legs.

Visible crew/equipment: When Jay enters the tent in which the small alien craft had landed we can clearly see the camera man in the golden reflection. This happens twice.

Continuity: In the scene at the lockers in Grand Central Station, Agent Kay takes his watch, an illuminated Hamilton digital, back from the little animals living there. In one shot, Agent Jay puts an analogue watch in the locker as a replacement, but in the next shot it is the same old Hamilton digital owned by Agent Jay. (This is mentioned in the DVD Audio Comentary with Barry Sonnefeld.)

Continuity: In the scene where Jay and Kay are talking in the mail truck, there is clear blue sky over the left shoulder of Jay. The camera turns to Kay for him to speak and when it goes back to Jay the sky over his left shoulder is cloudy.

Continuity: When Agents Jay and Kay are standing on the elevator overlooking MIB HQ when he brought Kay back, you can clearly see the leash (it's a small black string on Jay's finger) that Frank the dog is on in a couple of shots, then when they get off the string magically disappears.

Continuity: In the scene where Jay is fighting with Jarra, we see the clear rubber tubes in very back of the room. After defeating all the Jarras there is only six seconds left to stop the launch. He could not make it from the back of the room to the rocket in time to stop the launch.

Continuity: When Agent Jay is in the yellow tent with Serleena's tiny ship, he pulls out his video communicator and begins to talk to Zed. Zed can see Agent Jay via the communicator but when Jay closes the communicator and puts it away, Zed still has a view of Jay speaking with him over the big, egg shaped monitor. How could Zed see Agent Jay over the monitor if there was no video device available to transmit the conversation?

Continuity: When Lara Flynn Boyle is holding up Tommy Lee Jones with her tentacles, in one shot you can see the tentacles coming out of her fingers, but when they show her up close, there are no tentacles coming out of her fingers.

Continuity: When Agents Jay and Kay are in the elevator avoiding the garbage can robot who is shooting at them, watch their hands - they move from the wall to the roof ledge for support as the camera angle changes.

Continuity: After Jay and Kay go to see Jeebs about the deneuralizer, Kay leaves and the bad aliens come crashing through the walls. Jay shoots Jeebs head off and, as it's growing back, he says he got shot "right in the pie-hole" (mouth). However he was facing away from Jay when he was shot and it was above the mouth area.

Factual error: The opening of the film says it takes place in July 2002, but when we first see Will Smith you can see the World Trade Center in the background which had been destroyed ten months before. I know they made the film before the terrorist attack but mentioning the specific date makes it a mistake.

Other: About halfway through the film, there is a screw-up in the editing. After Serleena talks to the thugs, she proceeds to talk to Jarra. The next time we see her, she is interrogating Zed. Soon after, she is talking to Jarra as if she was never interrupted.

Continuity: During the fight scene with Jarra, Jay is dropped into the center of some large plastic tubing, but when the camera cuts to a closer shot, Jay is now seen at the edge of the plastic tubing.

Continuity: When Jay is giving Kay his favorite gun "little cricket" he is seen holding it by the lower part of the handle. The camera angle changes and he's holding it differently. The camera angle changes again and he back to holding it by the lower part of the handle.

Continuity: At the beginning of the movie, when Serleena first lands on Earth, her ship crashes into the ground and creates a mound of dirt. When Harvey the dog comes over to check it out, the mound is gone.

Continuity: When Agent Jay and Tee are talking in the diner, a young guy passes behind Jay towards Tee, but disappears when the angle changes.

Continuity: When Jay is trying to tranquilize Jeff he gets hit in the head by a crossbeam which lays him back on Jeff's back. You can see that the syringe is not in his hands or his mouth, but when he sits back up he has it in his mouth again.

Continuity: When Jay is in the fight scene with Jarra and his clones, Jay jumps up two clones to get to Big Jarra, but when the camera angle changes, the Jarra clone he jumped on is gone.