Continuity: The shotgun Edgar puts down in the morgue disappears.
Continuity: When K shoots Jeebs in the head in the jewelry store, the resultant blast sends goop flying everywhere, yet in the next scene, the counter and wall behind Jeebs is completely clean.
Crew or equipment visible: In the scene when the alien craft crashes, there is a shot of smoke rising, and off to the right side of the scene, men can be seen walking down the hill.
Audio/visual unsynchronized: When Edwards moves the table during the "best of the best" test, the scraping sound begins before the table is moved.
Errors in geography: When Agent K is looking up his lost love, he types "Truro", then zooms in on Cape Cod. As he closes in, he misses Truro on the map by about 50 miles' drive (the town/village he zooms to is actually closer to Forestdale or Wakeby). Also, the lush forest he zooms in on is all wrong; Truro has forests in the southern end of town, but of scrub pine trees, and North Truro is mostly dunes and grass.
Continuity:Kent Faulcon is identified as "1st. Lt. Jake Jensen" in the credits but calls himself "2nd Lt. Jake Jensen" in the audition scene.
Revealing mistakes: A pedestrian speed-walks past K's car window when they are first in the LTD, indicating sped-up film.
Crew or equipment visible: Partial reflection of the camera and its shadow can be seen when the camera follows the bank of lockers during J's initiation into the MIB.
Revealing mistakes: As J is being shown the screen where they constantly observe the aliens, the clips on the screen are being endlessly looped. A screen close to the center, for instance, shows a man getting comfortable on a couch over and over again.
Errors in geography: As J chases the alien at the beginning of the movie, the chase starts at Grand Central Station. In the next shot, the alien is seen running downtown (the park is on his right) to get to the Guggenheim Museum. The Guggenheim is uptown from Grand Central.
Continuity: The signs in the windows of the Russian restaurant change when shown from the inside.
Crew or equipment visible: When K approaches Redgick's car, the shadow of the camera can be seen briefly.
Continuity: The license plate on the LTD changes from centered to the right-hand side during the film.
Continuity: When Rosenburg leaves his shop, Edgar's "Zap 'em" truck is visible, reflected in the window. It is parked. The next shot of the street shows Edgar drive by and park in front of Rosenburg's shop.
Incorrectly regarded as goofs: When the car is going super fast and upside down near the finale, J falls upside down and you can clearly see what appears to be a white leg. However, that leg actually is that of Will Smith (as shown on the DVD version's special features).
Continuity: When K and J are talking with Z just before the "skimmer" problem is identified, K's legs are alternately crossed/uncrossed between shots.
Audio/visual unsynchronized: Right before K unplugs the camera in the interrogation he says "Some night huh?" but his mouth is not matched with the voice
Continuity: The address on the back of the MiB business card goes from being below the logo to above it.
Continuity: When the Mets player is hit on the head with the ball, he is wearing jersey #23. Later, when he is seen on the cover of the tabloid, he is wearing #20.
Revealing mistakes: When J is chasing the alien at the beginning of the movie, the alien leaps to the roof of the Guggenheim. When he does so, the cables aiding in the stunt are visible.
Continuity: The first time we are shown Orion's belt, his name is spelled out in all upper case (ORION). However, when Dr. Weaver examines his collar on her desk, it is spelled out in mixed case (Orion).
Factual errors: When K is looking at his lost girlfriend via satellite, the view is horizontal, as though shot from the ground, rather than "top down", as though shot from space.
Continuity: When K is giving J his weapon, the bug's spaceship can be seen behind J before the shoot out at Rosenberg's.
Factual errors: The exterminator's truck does not have a New York State DEC sticker, which is required for all pesticide application vehicles to have clearly on display.
Crew or equipment visible: As J is trying to follow Edgar after the gun fight outside the jewelry store, the pyrotechnic devices used for the cricket gun damage blasts are clearly visible for a few seconds before they burn out.
Revealing mistakes: When J goes into MiB for the written test with the other candidates, it is very apparent that the seal on the test is an architecture drafting dot, due to the noticeable Staedtler logo.
Errors in geography: In the end where the camera zooms away from Manhattan to the galaxy, the camera zooms from a location near the center of the Milky Way. According to most scientists, earth is actually located on one of the galaxy's "arms".
Continuity: When J tries to get the attention of K and Chief Zed for them to look at the spaceships in Queens, you can see K talking and typing on the keyboard, but his fingers aren't actually touching the keys.
Errors made by characters (possibly deliberate errors by the filmmakers): When Z shows J the screen diagram of Orion's Belt at headquarters, the three stars are labeled in reverse of their true order, and Alnilam is misspelled as Alinlam.
Errors in geography: K & J stop an alien in a car (the alien with the pregnant wife) because the alien is fleeing Manhattan, the area to which his visa restricts him. The alien's car is pointed toward Manhattan.
Crew or equipment visible: When the alien jumps off backward from the roof of the Guggenheim Museum, a safety cable can clearly be seen on his leg (just before the jump).
Errors made by characters (possibly deliberate errors by the filmmakers): After Jay passes the tests near the beginning of the movie and sits in the park discussing aliens with Kay, Kay comments that "1,500 years ago everybody knew the Earth was the centre of the universe; 500 years ago, everybody knew the Earth was flat". 1,500 years ago, only Europeans believed the Earth to be the centre of the solar system - the Greeks, Indians and most of the Moslem world had proposed and accepted theories of heliocentrism (i.e. the sun as the centre) several hundred years before Copernicus first published his theories on the matter in the 16th Century CE. The Earth's spherical nature was something that most scholars and all navigators were aware of as early as 400 BCE and has been common knowledge for the past 1,000 years.
Continuity: When the bug goes into the farm house wearing Edgar's Skin he drinks sugar water, and then Beatrice tells him that his skin is hanging off his bones. He looks in the mirror then grabs his hair and pulls his skin tightly to the back of his head. Beatrice faints and the next shot shows the bug still pulling his hair back, but the skin is no longer stretched.
Continuity: When Edwards is at MIB headquarters in the egg shaped chair he sets his test papers to his left side, then when he stands up to drag the table over the papers briefly disappear.
Errors made by characters (possibly deliberate errors by the filmmakers): When K wipes the memories of the cops on the Mexican border, he says the neuralyzer will isolate the 'electronic' impulses in their brains, when actually it's 'electrical' impulses.
Revealing mistakes: When J firsts shoots the MIB gun and is thrown back against the wall, it wobbles.
Continuity: After Edgar kills the Arquillians in the restaurant and rushes outside, we follow in a through-the-window shot as Edgar tosses a bystander off the sidewalk and then menaces a second in a close pass. But in the immediate exterior shot on Edgar from the sidewalk, the second bystander has vanished.
Continuity: When the Edgar alien crashes out the morgue window, carrying Laurel, white shorts can be seen sticking out from between Laurel's brown shorts, and her pantyhose. These do not appear again, despite numerous tumbles by Laurel that should have revealed them again.
Continuity: In the final scene, when Jay is fighting the big bug, he throws a rock and strikes the bug in the head. If you watch the rock closely, it disappears shortly after hitting the ground.
Revealing mistakes: As the Bug climbs through the hatch into the first spaceship at the World's Fair, the supposedly solid structure visible wobbles.
Incorrectly regarded as goofs: When riding in the tunnel, J puts on an 8-track and listens to Elvis. J quips, "You do know Elvis is dead?" to which K replies, "No he didn't, he just went home," implying he is an alien. Earlier K reveals the aliens first made contact in 1961 - five years after Elvis made his breakthrough performance on the Ed Sullivan show. However, this is when they made contact, not necessarily when they first landed.