Plot hole: Roger intercepts Riggs and blocks the path of his truck. After agreeing to a plan, we hear Riggs driving off. But his original path is still blocked and we don't see him pass behind Murtagh, so he must have reversed direction (which seems unlikely since he's continuing his drive to the same destination). But for his truck to have headed the other way, he'd have to turn it around first, but we hear it simply drive off.

Revealing: When the small car is launched into the air, the underside is plainly visible, showing no normal working parts like a suspension or drivetrain. It has a flat pan bottom with a square-tube support structure to make it very light for its flight and to retain it shape. (Director's Cut.)

Continuity: As Murtagh's car pulls up behind the small pickup, a man is reaching into the bed of the truck from the left side of the truck. But as soon as Riggs steps out of the car, the man is instantly behind his truck.

Factual error: Nail guns like the one used as a weapon here can not be fired unless the tip is pressed against a hard surface. It will not fire a nail at someone across any space. The first guy is killed by pressing the gun to his forehead, but the second is hit from several inches away (evidenced by the length of each nail still sticking out of the guy instead of them being fully into his body with only the nail heads showing.

Plot hole: In the opening chase scenes, the bad guys are using hand-held radios to communicate, and several shots show that all the police are hearing them. These professional criminals would not be broadcasting their criminal activities on a police frequency, nor are the police and their dispatchers monitoring scanners to pick up the criminals' frequency. So neither side should be hearing the other.

Other: In Lethal Weapon 1 Murtaugh turns 50. In Lethal Weapon 2, you can see a copy of Murtaugh's police file in the South African Embassy, when they are discussing repercussions against the police. In the file it says Murtaugh was born in 1947 which would make him 40 in this movie.

Continuity: Near the end, when Mel Gibson is captured by the bad guys they tie him in a straightjacket and toss him of a pier into the drink, he's wearing a pair of Dingo stlye boots. Underwater he does the shoulder dislocate thing and escapses the straightjacket, he sees Patsy Kendit's corpse, swims over, checks her pulse and swims to the suface. Now he's barefoot. Yet when he attacks and kills the two thugs he's got the boots on again. They can even be heared on the pavement.

Deliberate "mistake": The way diplomatic immunity is depicted in the movie is extremely inaccurate. While technically a sufficiently ranking diplomat could perform the acts shown in the movie without being subject to arrest, their home government would be requested to turn the diplomats over for trial, or the diplomat would be declared persona non grata and expelled from the country. A drug smuggling ring and murdering multiple policemen is far, far more serious than actual crimes that diplomats have been expelled (or handed over for trial) for in the real world.

Continuity: When Riggs and Murtaugh are trying to find the address Leo can't quite remember, Riggs is looking through an address book. Turning the pages, he gets to a yellow bit (possibly a different section), and so goes back a page. The angle changes half-way through this page turn, and the yellow page has disappeared, replaced with a page full of text.

Visible crew/equipment: When Riggs is thrown off the tow truck and rolls across the ground a camera peeks in from the right.

Continuity: When Riggs is thrown off the tow truck and rolls across the ground the Ryder truck that was just overtaken by the tow truck disappears and reappears between shots.

Revealing: When Riggs is holding on to the front of the tow truck, in some wider shots you see how his jacket is squeezed by the rope which ties him to the car.

Continuity: At the end of the opening car chase the red BMW crashes into a police car whose driver vanishes between shots.

Continuity: When the boss gives Riggs and Murtaugh the Leo assignment the name on the office door changes from Capt. E. Murphy to Capt. L. Murphy when they leave the office.

Continuity: In the final shoot-out Riggs shoots a guy who is looking down a ladder. We see about four exit wounds on his back, but no injury in front, neither later when Murtaugh takes a look at the corpse.

Continuity: When Riggs, Leo, and the bad guy crash through the hotel window they push the curtains to the side, but when they sail down into the pool the curtains are wrapped around them.

Deliberate "mistake": It's surely an intended joke, but that the toilet not only survived the explosion but also the landing in one piece is very unrealistic.

Continuity: When the helicopters approach Riggs' trailer it's late night, but from inside it looks as if sunlight is falling through the window (the little lamp in front could not provide such brightness.

Continuity: In the opening car chase the red BMW zips through a hotel arcade. On the right we see a guest waiting with a porter. The porter grabs a suitcase and runs towards the entrance, and the guest turns left and starts running away from the entrance. When the camera angle changes the guest is back where he was standing, but now he turns right and runs the other way.

Factual error: When Riggs and Murtaugh make the car go through the container door it has only a few meters to accelerate. It would have never been able to gain enough speed to leave the container almost horizontally.