Riggs and Murtaugh are vehemently anti-apartheid and take on Amoral Afrikaners in 2, but in 4, seem to think it's perfectly okay to make Asian Speekee Engrish jokes throughout (although to be "fair" mostly around the Chinese villains who make their money smuggling and enslaving other Chinese people; they are much more respectful around the non-villainous Asian characters).
To be fair, they did it only to Uncle Benny. Who does speak like that. It could be they're just insulting him considering they have had dealings with him in the past.
Contested Sequel: Whilst the first two movies are by and large considered buddy-cop/action classics, 3 and 4 are much more divisive. To some they are installments that have reached the point of self-parody in terms of their level of goofiness with things like the continued presence and pushing into center stage of the Leo Getz character as well as not having as strong of scripts after the departure of Shane Black. Whilst to others they while not as good as the first two are solid entries that continue to show off the great chemistry between its leads, match if not up the ante in at least some of the action scenes, and rounds off the story-arcs of its characters well. Particularly Riggs who finishes his progression from a crazed suicidal man to a more down to earth and at peace guy who can move on with his life and allow himself to be happy.
Crazy Awesome: Riggs "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.
In the first film, Riggs jokingly asks if the stock market crashed. Months after the film came out, Black Thursday happened.
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.
In the first film, one of the kids near Dixie's house says "My momma says policemen shoot black people!". It's a little more awkward these days, thanks to the high-profile police shooting of Michael Brown in 2014, spurring the emergence of the Black Lives Matter movement.
Part 3 opens with a terrorist blowing up a city building... as a punchline to a joke. Nine months later the World Trade Center was bombed, and the "joke" has only gotten less funny with each successive real-world incident.
Ho Yay: Riggs and Murtaugh are just loaded with this.
Memetic Mutation: Danny Glover has always been, and will always be, getting too old for this shit. Also, if you made it through the early 90s without hearing people quote "They FUCK YOU at the drive-thru!" everywhere you went, you must have been in a coma.
Mis-blamed: Many fans and critics credit the series' quality and success to writer Shane Black. However, many of the series' signature elements, including the humor, were added by Jeffrey Boam in his uncredited rewrites to the first film and screenplays to the second and third. Black's original treatments were considerably Darker and Edgier than the final product, with the character of Riggs being an unstable psychopath killed off at the end of the second film.