Continuity mistake: When past and future Boris meet, past Boris turns towards future Boris completely and has his full body facing future Boris as he is walking toward him. But as future Boris is still walking towards past Boris and saying the line about spending the next 40 years in prison, past Boris suddenly has his body turned away from future Boris, and so future Boris has to step around in front of past Boris. (01:12:45)
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)
Continuity mistake: As Boris says "I see you've brought me a treat, darling" to his girlfriend in Lunar Max, she turns her head from the guards and looks at the cake. It cuts to a closer view of Boris' face, and instantly she is looking at him instead of the cake. (00:02:50)
Plot hole: Lunar-Max prison is obviously part of MiB, them creating it for the purpose of holding Boris the Animal, and other criminals of worth as well. A high tech prison built on the moon with cutting edge technology and armed guards out the boot. Boris trashes the place, sounding all kinds of alarms and busting out, even blowing a sizable hole in the side of one of the complexes. He then jacks a ship off the moon's surface and crashes it back down to Earth. MiB doesn't know about it until almost a full day later when they realise the ship they found was from the moon, and Boris had escaped. It makes no sense that it took them that long to find out the information. A maximum prison, especially one to contain aliens on the moon, would be in contact with MiB. And any alarm that goes off there, especially for a break out of a high danger prisoner such as Boris the Animal, would have sent an alert to MiB headquarters right off if there was any logic to their system at all. There is only about a 1.5 second delay for a message traveling at light speed to reach Earth from the moon due to its distance. So within seconds of Boris busting out, MiB should have already been mobilizing to track where he would be going and intercept. There's no way, that logically, Boris could have escaped, made it back to Earth, and been there for nigh a day without MiB knowing about it and having their agents already tracking him down. (00:03:55 - 00:14:25)
Suggested correction: Boris made his escape and trip to Earth in a matter of minutes, of course MIB were tracking him in that time, it's just not shown on screen.
Continuity mistake: After O delivers her eulogy for Z, J and K are in the car talking. The amount of cars and the style of the streets they pass-by have no continuity whatsoever between front and side angles. (00:09:40)
Factual error: When J goes to the electronic store to get the time jump piece from Jeffrey Price, all of the TVs in the store are showing "Wheel of Fortune", which in NYC is shown on ABC TV channel 7. But when the show is interrupted for the emergency story about the invasion, the TVs show NBC TV Breaking News, which is channel 4 in NYC. (00:32:05)
Continuity mistake: At the headquarters, when young K places the neuralyzer and gun on the table their position changes between shots. (00:44:00)
Plot hole: At the ball park stadium, K, J, and Griffin are high up in the bleachers watching a future window of the Mets game. Boris suddenly drives by on a motorcycle up in the stands and grabs Griffin, then plows through the railing on the side of the stadium and falls down below, crushing K's car. He then speeds off instantly out of the parking lot with Griffin. Then suddenly, somehow, J and K are running out into the parking lot close to their car quickly enough to be watching Boris speed away from the parking lot on the road. There is absolutely no way K and J could have made it out of the stadium and out into the parking lot in just a couple of seconds like that. (01:09:05)
Continuity mistake: When young K starts questioning J, K's hands swap between crossed, loose, one on top of the other with no continuity whatsoever. (00:43:35)
Continuity mistake: In the lunar prison, when the guard puts his hand inside the cake, his sleeve is by his wrist or rolled up to the elbow, depending on the shot. (00:03:10)
Continuity mistake: After the bug in the cake kills the cops, it runs to free Boris. The amount of strawberry cake on the sewer lid changes between shots. (00:03:25)
Continuity mistake: In the scene where J and O are talking about the temporal rifts (just before they are alerted to the invasion of Earth) the ring on O's left hand keeps disappearing and reappearing. (00:29:45)
Factual error: When J arrives on top of the bird on the Chrysler Building in 1969, he looks around at the view. The North Tower of the World Trade Center (One WTC) should be in view. The construction of the North Tower began in the summer of 1968. In 1969, even though the very top was still under construction. The first tenant moved in. Even though One WTC wasn't officially finished until 1972, in July 1969, there should be a clear view of at least 3/4 of that tower. (00:37:20)
Deliberate mistake: The Army Colonel's Class A uniform does not have a name plate on the flap of the right breast pocket as per regulations. If the Colonel's name plate was present, there would be no twist to the movie. (01:21:50)
Continuity mistake: When K takes the prize out of the Crackers box, the size of the box magically becomes very tiny. (01:07:55)
Continuity mistake: When Jeff sets the box with the time device in it on the counter, he begins to open it with one hand on the side of the box, and the other hand on the front of the box. It cuts to a close up and suddenly his hands are both on the sides of the box. (00:33:05)
Continuity mistake: When the racist cops are frisking J, one pulls out J's gun and questions him about it. In the reverse angles, the cop is holding the gun over J's shoulder with almost all the handle in his hand. In the shots showing J's face, the cop is holding the handle so that some of it is sticking down, and it is in front of J's shoulder. (00:41:00)
Continuity mistake: This movie starts in 2012 as shown on Zed's memorial, then travels back to 1969, 43 years earlier. But J tells the young K "25 years from now you're going to recruit me, and 14 years after that, the guy you didn't let me kill today..." That's only 39 years. (00:47:55)
Continuity mistake: When J falls off the green car by The Factory, cardboard boxes, a woman and a sailor magically appear out of nowhere. (01:01:40)
Continuity mistake: When Boris blows the prison door and encounters hundreds of guards, the damage on the door changes between shots. (00:04:50)