Revealing mistake: When Austin enters the bathroom at the casino, keep your eyes on the door during the scene - it opens by itself before closing. (00:31:10)
Plot hole: When Andy turns into a werewolf, he kills both Amy and Detective Benbou. Later in the morgue, Amy tells him because of this that she is forced to become his "rotting sidekick." If this is completely true, then Detective Benbou should also be following Andy around but he isn't seen after Andy manages to escape from the morgue.
Continuity mistake: When Chris Farley is pretending to be a Chinese cook at that one restaurant, cooking, the brown spot on the stove keeps on changing size.
Continuity mistake: When Sam and Anton are finished fighting (Anton is in an upper-body cast), the arm support on his right keeps changing. First it's a short piece coming from the elbow, then it is a long piece coming from the side, and then back again.
Visible crew/equipment: When Nisi and Mickey first walk into the bathroom Mickey asks why there are two toilets, and in the next shot the microphone pops up into view at the bottom of the screen.
Visible crew/equipment: The cameraman is visible in the reflection of window while Holden is walking back to his car in the rain.
Revealing mistake: When Fletcher is beating himself up he goes into a stall and squishes his head with a toilet seat. You can see that the white part underneath is made out of foam because it keeps squashing down.
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 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: 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.
Plot hole: When Leo, Gustav and Himmel are driving through Miami looking for Pest, Gustav notices that the tracking device that was put in Pest's underwear shorted out because of how much he was sweating. An earlier scene showed that Pest jumped off a boat in the middle of the ocean and swam to Miami. Since the tracking device was in Pest's underwear the whole time, it should have shorted out the moment he jumped into the water leaving Pest safe and Leo, Himmel and Gustav driving around aimlessly.
Continuity mistake: In the scene where Lyle and Ursula slide through the river then over the falls, when they go over the waterfall they are both dry.
Continuity mistake: At the beginning of the movie, when Clark is driving down the street looking at the map, there are 4 kids roller blading in the street. In one shot, one of the kids jumps onto a parkway lawn to avoid being hit by Clark's bad driving. Next shot, when they pan back to the kids, all 4 are still on the street.
Visible crew/equipment: The camera searches for Dora whilst Guido plays music through the open window. In her room, you can easily see a cable (from a microphone or a spotlight?) on the left side of the screen. (01:42:00)
Visible crew/equipment: When the dad gets in the big accident, as he swerves the truck, you can see a hand reach out and grab him.
Continuity mistake: In many places in the movie, a cat noise is heard even though the cat's mouth is quite obviously not open or the cat is licking its face.
Continuity mistake: When Robin Williams puts the flubber into his back pocket to show Sara how it will bounce him back up, you can clearly see a hole in which the flubber escapes. When he falls to the ground and Robin Williams turns over the hole is gone.