Richard Donner asked Jet Li to slow down during action sequences, because he was moving faster than the camera shutter speed, and it wasn't registering on film.
Originally the final fight was supposed to be between just Riggs and Wah Sing Koo. However after a rehearsal where Jet Li not only blocked Gibson's punch, but delivered at least 20 blows to the actor too fast for the camera to see until the footage was slowed down, it was decided that there was no way the audience would buy Riggs defeating Wah Sing Koo alone.
Murtaugh's boat is named "Code 7", which is the L.A.P.D. radio code for a lunch break.
Jackie Chan was considered for the role of Wah Sing Ku, but turned it down, because he chooses never to play the villain in a movie.
The car chase and fight between Riggs and the Chinese man in the house trailer was filmed on I-215 in Las Vegas, Nevada. Apparently, they couldn't get filming permission anywhere else, but the Las Vegas mayor was very accommodating. All drivers were either stunt drivers, or members of Bill Young's Driving Team.