Directed by: Richard Donner
Starring: Mel Gibson, Danny Glover, Chris Rock, Jet Li, Rene Russo, Joe Pesci, Kim Chan, Steve Kahan
Factual error: Riggs shoots Ku to death with the AK-47 underwater. Guns can fire underwater, but the bullet loses most of its killing velocity. This would have been unable to kill Ku.
Suggested correction: If Wah Sing Ku was far away, this would be true. But Riggs is shooting with the barrel pressed directly against Wah's chest. It's definitely lethal at that range.
Continuity mistake: During the car chase involving the car driven by the Chinese guy, Murtaugh, and the mobile home, the two cars slide against each other and the right wing mirror on Murtaugh's car is completely wrecked. Once the two cars are separated the wing mirror has miraculously repaired itself. The left wing mirror also does a disappearing / reappearing trick.
Lorna Cole: You look a little banged up.
Martin Riggs: Well, you look a little knocked up.
Question: In the beginning of the movie when the tanker truck gets blown up, why does the fully intact truck just get launched straight up with flames below it? The source of the explosion would be the truck itself, so when ignited, the truck should have simply been blown up into a million pieces, not launched straight up fully intact.
Answer: This was most likely done just to make the scene look that much cooler. Movies do things like this all the time.