Deliberate mistake: When Riggs is chasing the guy on foot, you can clearly see it is a stunt double, who is also very apparent in other shots throughout the film.
Lethal Weapon 4 (1998)
1 deliberate mistake
Directed by: Richard Donner
Starring: Mel Gibson, Danny Glover, Chris Rock, Jet Li, Rene Russo, Joe Pesci, Kim Chan, Steve Kahan
Revealing mistake: During the big gun battle right before the last fight scene, Riggs is shown driving a forklift, and knocking over some barrels on top of Wah Sing Ku, leader of the Triads. When the forklift does the 180° turn, you can see that it is not Mel Gibson, but an Asian stunt man.
Roger Murtaugh: You ever hear of Ebony Clarke?
Martin Riggs: Yeah, she writes those cheesy sex novels. Why? You boinkin' her?
Roger Murtaugh: No I'm not boinkin' her! Trish is Ebony Clarke!
Martin Riggs: Oh, so you ARE boinkin' her.
Roger Murtaugh: Yeah... Yeah, I'm boinkin' her!
More trivia for Lethal Weapon 4
Question: I wonder, what was the point of having a gunfight with the armored man at the beginning of the film?
Answer: It was put in the film to introduce the concept of Rianne and Lorna being pregnant and to bring in the joke about the news article about Roger, not to mention giving the film an action-heavy opening.