These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
YMMV: Lethal Weapon
Complete Monster: Wah Sing Ku, who kills a money counterfeiter's uncle to persuade him to continue his work. And lets not forget his smirking willingness to burn Riggs, Murtaugh, Trish, Lorna and Ryanne alive.
General McAllister and Joshua's torture of Riggs and Martaugh was pretty cruel and brutal, especially for having Ryanne watching her father while being beaten.
Mc Allister's far worse in the novelization: when it becomes clear Murtaugh isn't going to break under torture, he tells him that he's going to have two of his men become "double veterans". That involves them raping Ryanne in front of him, and then killing her. He also tells Joshua that he truly believes their heroin trafficking is helping America, by keeping "lesser" races downtrodden and addicted.
"You think I'm crazy? You think I'm crazy, I'll show you crazy!" *proceeds to slap himself in the face multiple times while wailing like Curly from The Three Stooges, pokes the drug dealer in the eyes, slaps the other drug dealers, and pulls out a gun.
Even Better Sequel: Donner, Gibson, and Glover all consider the second one to be this.
"Funny Aneurysm" Moment: Riggs mocks Rudd's racism and calls him "Aryan" in the second film. Cut to 2006, and Mel Gibson is in hot water for making several racist remarks during his arrest. Cut to 2010, and he's in even more hot water for making even more racist statements during an argument with his girlfriend.
Mel Gibson's character getting "married" by a Rabbi in the fourth film.
Memetic Mutation: Danny Glover has always been, and will always be, getting too old for this shit.
Sequelitis: A not too drastic example, but most noticeable with part 4.
Values Dissonance: On two separate occasions in the first film, Riggs demonstrates extreme homophobia. Perhaps fair for its time in 1987; stands out quite a bit in 2011.