Lorna is pregnant with Riggs' baby and both he and Murtaugh are contemplating the implications of growing older. Meanwhile, Riggs and Murtaugh receive a brash younger detective named Lee Butters (Chris Rock) and are dealing with Chinese Triads when they uncover a boatload of illegal immigrants. The Dragon (In Chief)/Big Bad of this group is Wah Sing Ku, played by Jet Li, by whom Riggs finds himself entirely outmatched.
- Actor Allusion: Kim Chan (Uncle Benny) says, "Bloody marvelous!" a catchphrase often used by his character The Ancient in Kung Fu: The Legend Continues. This also isn't the first time he played a crime lord named Uncle Benny.
- Artistic License Gun Safety: Wah Sing Ku disassembles Riggs' Beretta... while Riggs is holding it and trying to shoot him (which is physically possible with a Beretta due to its design, so it's not just Hollywood trickery, but definitely Awesome, but Impractical).
- Artistic License Physics:
- Riggs' laser trick shooting in the start of the film at the tanker, with the laser sight going being able to ricochet from a surface.
- Making that particular sequence worse, the laser is clearly pointing to the winch's upper curve. Assuming the laser is accurate, there's no way Riggs could have even accidentally made that shot.
- Also in the same scene, barrels of flammable liquid are not ignited by gunfire, and they do not detonate and launch like missiles using the bullet holes as exhaust ports.
- Riggs' laser trick shooting in the start of the film at the tanker, with the laser sight going being able to ricochet from a surface.
- Avenging the Villain: Wah Sing Ku attempts to flee Riggs and Murtaugh with his brother, as all the other Four Fathers have been killed. When Murtaugh shoots Ku's brother while aiming for Ku himself, Ku sticks around and tries to kill Riggs and Murtaugh in revenge. Riggs then shoots Ku underwater after they fall off a pier while fighting.
- Battle in the Rain: The opening shootout with the human tank occurs while it's raining, and the final fight with Ku takes place in an intense rainstorm on a pier.
- Bash Brothers: Riggs and Murtaugh embody this trope during the final fight against Ku, who is much younger and faster than them.
- Bloodier and Gorier: The film is considerably more violent than its predecessors, with its Big Bad getting graphically impaled through the midsection and drowned.
- Bottomless Magazines: Averted, everyone ends up having to reload, from the flamethrowing psycho at the beginning of the movie (he reloads his assault rifle) to Riggs and Murtaugh at the end of the movie ("Alright, I'm gonna go find us some more ammo!"). Interestingly, Riggs actually does shoot through about three magazines of ammunition in his Beretta in the final battle, and Murtaugh is notably cautious about how many bullets he shoots: police officers generally carry a loaded weapon and two reloads (45 bullets for Riggs, 18 for Murtaugh).
- Catch Phrase: Ku's "If this was Hong Kong, you'd be dead", which refers to the criminals in his home turf handling unpleasantries more efficiently.
- Chekhov's Gunman: Little Ping, who saves Riggs, Lorna, and the Murtaughs along with Rianne from a burning house.
- Corrupt Bureaucrat: The State Department official who accepts a bribe from the Triads to create fake passports for the Four Fathers, and the Chinese general waiting for a larger bribe to free them.
- Creative Closing Credits: The end credits has pictures of the cast and crew with "Why Can't We Be Friends" playing in the background, mostly because everyone knew this would be the last in the series and they wanted to celebrate it.
- Destroy the Product Placement: The car chase scene between the 98 Pontiac Grand Am and a Mercedes Benz 420 SEL (with the former being driven by Roger and the latter by a criminal) ends with the Pontiac being partially damaged by crashing through an office and suffering some damage by a truck. That same truck ends up ramming the Mercedes Benz.
- Dies Wide Open: Murtaugh discovers Hong's corpse this way.
- Dirty Cop: Played for Laughs and Averted. Lorna says Internal Affairs got an anonymous tip that Murtaugh was on the take, though it is clear they don't take it seriously. Riggs doesn't either, but then he notices that Murtaugh has an unusual amount of money eventually he confronts him about it, asking how he can support his family, get his kids though college, rebuild his house and buy a fishing boat on a Sergeant's salary. Murtaugh is reticient, and this drives a wedge between them. It turns out that his wife has written several Mills and Boon Prose-heavy Romance Novels (Riggs describes them as "the cheesy sex novels") that sell extremely well, and he's been embarrassed about where the money comes from.
- Disarm, Disassemble, Destroy: Ku dismantles Riggs' Beretta to end the Mexican Standoff between them in a scene that establishes him as a serious badass.
- Doctor, Doctor, Doctor: Riggs and Murtaugh get promoted to captain unexpectedly. They respond by calling their usual captain, each other, and even themselves "Captain" incessantly.
- Dragon-in-Chief: Wah Sing Ku is technically working to free his bosses, one of whom is his older brother. But since they are all in prison he's the one who actually drives the plot.
- Dramatic Thunder: In the final fight with Wah Sing Ku.
- Every Car Is a Pinto: A car driven by some Triad Mooks try and ram Riggs' car into the path of an oncoming train. By cleverly pulling ahead, Riggs leaves them on the tracks instead, and their car is hit by the train, blowing up from the impact. Then the burned out wreck lands on the parallel tracks and get hits by another train going the opposite direction, causing it to blow up again.
- Evil vs. Evil: The cops deliberately trigger this by revealing to a faction of corrupt Chinese soldiers that their Triad business partners are trying to rip them off. Riggs takes an awfully sensible view of the subsequent shoot-out:Riggs: Keep your head down, Rog! Let them kill each other!
- Famous Last Words:
- "What job?" Hong
- "What do you want?" General
- Flamethrower Backfire: The opening scene has Riggs do this to a flamethrower-toting bad guy, shooting a vent on the guy's equipment which sends him to an explosive death.
- Fridge Brilliance: One instance actually happens in-universe, and is not trivia. Note the quotation below is also Casual Danger Dialogue.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: Trish is Ebony Clarke!? ...So you are boinkin' her!
Roger Murtaugh: [realization followed by a big grin] Yeah...! Yeah, I'm boinkin' her!
- Goofy Print Underwear: When Murtaugh is directed by Riggs to strip to his boxer shorts to distract a madman wielding a flamethrower, Riggs asks with a laugh "Are those little hearts?"
- Grand Finale: Of the series.
- Guns Do Not Work That Way: No, a Laser Sight can not allow you to perfectly chart a ricocheting bullet's path. It can't reflect its beam off a rusted pipe, either. Suffice to say the Artistic License on firearms was rather heavily invoked throughout the entire series.
- Hair Today, Gone Tomorrow: Riggs has shorter hair in this movie.
- Heavily Armored Mook: The flamethrower and machinegun wielding lunatic at the start wears heavy metal armour that makes him impervious to bullets.
- Hoist by His Own Petard: A more comedic example would be when Riggs wants to ask the police psychiatrist for legitimate advice regarding his intent to marry Lorna, but his years of mocking her makes her instantly go on the defensive and assume he's trying to punk her again. So he then turns around and punks her for real.
- Honor Before Reason: In the climax of the film, Riggs and Murtaugh have successfully thwarted the bad guys' plans. But they killed Ku's brother, leaving him seriously pissed. They had more than enough time to make their exit and stay away from Ku's wrath and even begin to walk the other way, talking about coming back with a howitzer or something like it. But then Riggs starts musing about Ku's crazy gun dismantling trick he pulled earlier in the film and they realize they have to face him to end it.
- Improbable Aiming Skills: Brutally deconstructed. Murtaugh tries to kill Wah Sing Ku with his head-cocked shooting. Ku is able to dodge, but the bullet hits and kills his brother behind him.
- Insane Troll Logic: When Riggs and Murtaugh are looking for the Triad thugs who just tried to kill them, they ask a chopper to look for the car they took off in. A black Mercedes on a certain part of the freeway. The chopper says they've got two cars that match that description, one heading east, one heading west. Riggs, who's driving, says they're following the one heading East.Murtaugh: "How do you know we're chasing the right one?
Riggs: "I don't know, but we're going east, and China's east, so..."
Murtaugh: "Yeah, but China's west too, Riggs."
- Invincible Villain: Wah Sing Ku is easily the most dangerous and hardest to bring down villain in the entire series, and perhaps the most badass character in it. He is a Lightning Bruiser who can beat the tar out of you with his kung fu, strangle you to death in a second with one hand, take apart your gun in a flash while you are holding it, and at one point literally dodges a bullet. It takes Riggs and Murtaugh working together to finally bring him down and they only win because he is blinded by rage and they have to fight dirty. Even then, they both end up with broken bones and nearly killed themselves, being visibly older and in nowhere near as good a physical shape as him doesn't help.
- Kicked Upstairs: Riggs and Murtaugh are both promoted to Captain in the hopes that giving them desk jobs will cut down on the destruction they cause in the city. It doesn't work, and they're busted back to Sergeant by the end of the movie.
- Locked Out of the Loop: Played for Laughs on Murtaugh, regarding the identity of Rianne's husband, which even Riggs knows.
- Made of Iron: Wah Sing Ku, who gets impaled with a rebar and still continues fighting. In fact, it took a full burst from an AK-47 to the torso while he was underwater to finally take him down.
- Mêlée à Trois: The final shootout is between the police, the Triads, and the Chinese military.
- Minor Crime Reveals Major Plot: A ship full of smuggled Chinese immigrants → A plot to sneak four Chinese Triad bosses into the country.
- Mistaken for Gay: Butters was trying to be nice to his father-in-law. He instead thought that he had the hots for him.
- "El Niño" Is Spanish for "The Niño": When Riggs, Murtaugh, and Butters seek to question Uncle Benny at a dentist's office, they give him a dose of laughing gas to make him more complacent, except they give him too much gas, making him way too aloof and carefree to be very helpful. His one clue as to the location of the Hongs is "Renminbi". When asked what that means, Uncle Benny explains, "'Renminbi' means... 'Renminbi'." note
- Oh, Crap!: Done by Wah Sing Ku before he gets shot to death underwater.
- Older Hero vs. Younger Villain: Wah Sing Ku is younger than both Riggs and Murtaugh and very skilled in a deadly form of martial arts.
- Outranking Your Job: Riggs and Murtaugh both get promoted to captain, but the promotions seem to carry no real weight. Neither is assigned any subordinates or additional responsibilities, and aside from Riggs occasionally announcing, "This is your Captain speaking!" to colleagues, both continue to chase criminals as if they were sergeants — though the whole point of promoting them was to get them out of the field.
- Pregnant Hostage: Wah Sing Ku and his Mooks force Riggs and Murtaugh to stand down in a Mexican Standoff by dropping their guns, but taking Lorna and Rianne and holding them (and their pregnant bellies) at knifepoint.
- Reality Ensues: Hero Insurance is not part of the package when you join the police service, so Riggs and Murtaugh are Kicked Upstairs in a (vain) attempt to stop them engaging in destructive car chases and causing explosions while they are saving the day. Since it doesn't work, they get demoted back to Sergeants at the end of the movie.
- Conversely, Murtaugh is deeply hurt at the accusations of corruption and it takes most of the film for Riggs and Murtaugh to start talking to each other again. Some things can't be said, no matter how close you are.
- Ruthless Foreign Gangsters: Wah Sing Ku and the Triads. Lampshaded when Wah Sing Koo actually complains that back in Hong Kong, everyone who crossed them or failed them would be dead, but he has to show more (relative) restraint in America.
- Screw the Rules, I Have Money!:Wah Sing Ku: Brother, America has many laws, but written by men. Money can change everything.
- Super Speed: They had to get Jet Li to slow his fight scenes down because he was too fast for the actors to react to and the camera to catch on film.
- Starter Villain: The nameless flamethrower-toting man rocking out to Gary Cherone-era Van Halen who Riggs and Murtaugh confront in the prologue.
- Survival Mantra: "We're not too old for this shit... we're not too old for this shit..."
- Take That!: The film contains some shockingly unsubtle jabs at the expense of the National Rifle Association. This is a series that elevated dangerous and irresponsible gunplay to an art form and generally gives the middle finger to gun safety.
- Taking the Bullet: Butters does this in the final battle when a Chinese soldier is about to shoot Murtaugh from behind. Unlike most examples, it's not fatal.
- The Triads and the Tongs: The main villains of this movie.
- Tragic Keepsake: Murtaugh finds the watch he gave to the elderly Asian immigrant he befriended...
- Trash the Set: Murtaugh's boat gets blown up during the fight on the smuggling freighter, and his family's house gets burned down by the Triads.
- Uncle Tom Foolery: Averted, as Lee saddled to two heroes, one of whom is black and plays a middle role of being neither insane nor too by-the-book.
- Video Credits: All the actors are shown alongside stills of themselves in the movie, going with the photo album nature of the Creative Closing Credits.
- Villainous Valour: Only Wah Sing Ku is able to disassemble a Beretta in 5 seconds with his own bare hands and then knock out Riggs and Murtaugh who are older and taller than him. In the final showdown he once again manages to handle them even if they are two vs one.
- What a Senseless Waste of Human Life: Butters' Establishing Character Moment shows that while he accepts the idea of lowlifes or even fellow cops getting killed (as he describes it, "occupational hazard"), he gets pretty upset at a normal civilian being the victim of a murder. Riggs and Murtaugh even have to tell him to calm down. In retrospect, he was probably exaggerating a bit to look good in front of Murtaugh, that is, morally good enough to be married to his daughter.
- What Happened to the Mouse?:
- The third Four Father must have somehow disappeared when the other two Four Fathers were being shot by the General before the final shootout and when Ku and his brother fled.
- Also, Ng and his partner aren't seen anywhere after the shootout commences and when Murtaugh tells Ng to look after Butters.
- The Worf Effect: Done interestingly. Riggs realizes his age when the freighter captain handily kicked his ass. But Ku ends up dispatching the captain with embarrassingly little effort, proving that he will be quite an enemy to beat.
- You Have Failed Me: Wah Sing Ku does this both to the freighter captain for losing the Hong family (as well as the entire shipment of Chinese), as well as Uncle Benny for generally disappointing him.