8. Lethal Weapon 4
One of the most fascinating parts of Lethal Weapon as a series is the oscillating tonal battles that took place behind the scenes. The first film, written by Shane Black with some rewrites by Jeffrey Boam, is this gritty, post-Vietnam action film that tackles PTSD and the legacies of the conflict, while the second is a fun, slightly goofball adventure that sees Riggs and Murtaugh take on some apartheid gangsters while Joe Pesci tags along with the challenge of saying "okay" more times than any other actor in a single film. (Love Leo really.)
Lethal Weapon 2 was almost very different though. Black's script was tossed aside in favour of a rewrite from Boam, which toned down the darkness, and aborted an ending where Riggs would've died. Boam returned for the decidedly less-precise Lethal Weapon 3, retaining the previous film's antics but with a clumsy focus on gun crime. Lethal Weapon 4 course corrects ever so slightly, but it's not the gritty original nor the high-octane fun-fest that is the first sequel.
This is because Jeffrey Boam wasn't responsible for the Lethal Weapon 4 shooting script. Boam had developed a screenplay - one that would have, ironically, tapped into the dark roots of the Shane Black original by having Riggs and Murtaugh go up against Neo Nazis - but it was set aside by the studio, who ostensibly wanted LW4 to focus on the Triads.
Boam's script appeals way more on premise and reputation than what we eventually got - even if Lethal Weapon 4 (mostly) succeeds as a franchise send-off.