Continuity mistake: When Agent Kay empties his guns shooting at the trashcan robot in the elevator, he throws down his guns and swings back to the roof of the elevator. When the robot moves into the elevator, the guns are nowhere to be seen. (01:03:00)
Continuity mistake: Right after Zed kicks Serleena in the face a few times, you see Serleena tripping him with the vines from her fingers and he lands on his side. The camera angle changes and he is now seen laying flat on his back. (00:44:40)
Continuity mistake: When Jay and Tee first start to talk to Jeff, Tee grabs the "weed." When Jeff gets mad and starts banging on the grate, the wide shot shows Tee in the same position, gripping Jeff's weed, however it was not digitally added in that shot, so he's gripping nothing. But in the next shot, he's shown gripping the weed again.
Continuity mistake: Throughout the whole movie when someone is driving they keep driving to different locations but if you look out the window it's just the same green background all the time. (02:27:09)
Continuity mistake: The entrance room (the large stone building off Battery Avenue) to the starport reverses between the two movies. In the first movie, the guard sits on the right hand wall as one faces the elevator, with a fan visible through a grille behind him, and a circular vent on the other wall. In MiB II, he is sitting against the left hand wall, but the fan and grille is still behind him, meaning it has changed walls. (00:17:15)
Continuity mistake: When Agent J drives to see the small, gold alien ship in the yellow tent, he steps out of his car and into a small amount of mud. His shoes already have mud around the soles and edges when he steps out. (00:24:30)
Continuity mistake: Before the alien transforms into a woman it flips the pages of magazine located inches away. When the alien starts to transform the magazine disappears. (00:05:10)
Continuity mistake: After being flushed, the amount of water on J's chin increases in the close-ups, but decreases in the wide angles. (00:35:35)
Continuity mistake: At the post office, K waves his hands at J and turns around to where the employees are. When the angle changes K is waving his hands again.
Continuity mistake: At Jeebs' basement, an alien lifts up J, placing his hand on Jay's right shoulder. When the angle changes, the hand is on the left shoulder. (00:43:00)
Continuity mistake: At Jeebs' basement, an alien launches J away and he lands facing to the left. A frame later his head is facing to the right. Also, his arms have changed positions. (00:43:00)
Continuity mistake: When Jeebs is about to start the deneuralizer, watch the left part of the chain around the computer screen; Sometimes a tip of the screen is visible, others not. This changes back and forth. (00:40:10)
Continuity mistake: Serleena's ship lands completely perpendicular to the ground, but when the angle changes it's pointing a 2 o'clock position.
Continuity mistake: At Jeebs' basement, when Scrad comes to talk to J, J's tie swaps back and forth between tight and loose. (00:42:25)
Continuity mistake: When they land on the roof of the launch site, Jay gets out of the passenger side, even though he and Kay switched spots after which Jay was driving/flying.