Continuity mistake: When they are running the obstacle course, the amount of hoops in front of the girls changes from five, to two, to five again.
Audio problem: When Will Smith is looking at the two space ships at the MIB headquarters, if you look in the background Zed and K are there typing on the computer. But if you look closer you can tell that they're not even touching the keyboard and the sounds are just added into the movie. (01:16:00)
Continuity mistake: When George takes her to the airport (in NYC), they are at O'Hare. Later, when she gets off the plane, she's still at O'Hare.
Continuity mistake: When the kid rescues Bud from his former owner, Bud's paws become all muddy when the faucet breaks. In the next scene they are running down the road and Bud's paws are clean.
Continuity mistake: The whole big prison bus escape scene revolves around Chris Tucker being handcuffed to the French guy, but when Frenchy's friend arrives in the bus he stands up and hugs him while the handcuff is shown completely unlocked from Tucker's hand. In the next shot and the entire next scene they are still handcuffed together.
Continuity mistake: At the beginning of the movie when Romy reunites with Heather Moony, Heather tells Romy that she invented the cigarette which she is smoking and takes a puff to show how fast it burns down, and the cigarette burns to the butt. But in the next scene her cigarette is still to its half-way point. (00:07:25)
Continuity mistake: In the beginning of the movie, when the little girl is falling, they film her falling all the way down backwards. When they flash to the young Simon's face and the priest and back to the girl she lands face down.
Visible crew/equipment: In the shoot 'em up scene at the hangar near the beginning of the film, right after Tito and Wanda take down Pollux, when Troy shoots an agent in the stomach and the agent flies back - you can see at least two cable wires pulling him backwards. You can first notice the 2 wires when the agent is running in slow motion right before he shoots him. (00:14:15)
Other mistake: When the slaves are getting into the Portuguese ship (the "Tecora"), the crew shouts in clear Spanish (some Spaniard and some Mexican accent) rather than the expected Portuguese. (01:18:10)
Factual error: Just before Declan and the Jackal start shooting at each other in the subway tunnel, one of the trains starts coming from the opposite direction and begins passing Declan. This train continues to pass him at full speed for a full 35-40 seconds while they shoot it out. Subway trains are not nearly long enough for that. Also, during this time another train comes from behind him and he has to get between them and hold onto the light for a few seconds while they pass. But the second train then passes first while the first one passes fully about 2 seconds after the second one came... and it got there first, by about 15-20 seconds. Subway lines are about the same length as each other as well. But the first one was way longer and way wrong. (01:49:30 - 01:50:05)
Revealing mistake: When the killer is attacking Cici on the balcony, you can see blood on Cici's back before she is even stabbed and both times she is stabbed, the knife that comes out of her back has no blood on it. (00:33:20)
Continuity mistake: When Lolita begins to undress in front of Humbert, she is wearing her school uniform. Her shirt first appears tucked in, then out and then in again.
Character mistake: When they're on the island and the INGen helicopters are flying in, Jeff Goldblum takes the binoculars and looks through the wrong end. (00:32:30)
Revealing mistake: When Batman places the heaters around the telescope to thaw the ice, the frozen floor moves like plastic when he places the second heater. (01:45:00)
Audio problem: When Chris drives up in the truck while Selena is mowing the lawn, Selena asks what he got. While you hear "junk food" his mouth says something else.
Factual error: In the beginning of the film, the Dowager Empress Marie states that the year is 1916 and that they are celebrating the 300th anniversary of their family's rule. The 300th anniversary actually took place in 1913. (00:01:05)
Plot hole: Barry gets killed violently at the pageant. So obviously there should be blood everywhere. When the police go up to the crime scene, they find nothing. There's no way the killer had time to clean up anything, let alone drag away Barry's body without someone seeing him. And blood starts dripping after the police leave the scene.
Continuity mistake: There's a scene where Ellie sleeps with Palmer, then gets up quickly to go to the lab. In her haste, she departs whipping on a shirt with no bra. If she had a bra inside that tight T-shirt the contours of the cups and straps would be visible and we would see her fitting and fastening it, instead she steps outside where suddenly it appears she is now wearing a bra.
Continuity mistake: Toward the end, Carmen Ibanez gets stabbed through the shoulder when she is brought before the big master alien thing. If you were to sustain such an injury, there would be so much swelling, not to mention just destroyed tissue, that you wouldn't be able to move that arm for weeks. Yet a few minutes later, she is seen hefting around a very large assault rifle, and seems to have no difficulty. I guess it's a pretty standard action movie "heroes can temporarily ignore injury in order to save the day" kind of oversight, but it just seems exaggerated in this case, considering how severe the shoulder trauma looked. (01:48:15 - 01:53:40)
Continuity mistake: There's a part when Raiden, Liu Kang, Kitana, Jade Jax and Sonya are confronted by 3 ninjas and Sindel. Raiden decides to take on the ninjas, but you'll notice that he only fights against 2 of them.