Hard as it is to believe, the original "Lethal Weapon" turns 30 this year. Well, maybe not that hard when you take a gander at Mel Gibson's mullet...

But even after all these decades, Detectives Riggs and Murtaugh are anything but too old for this s***. To celebrate this milestone, join us as we explore some interesting facts you might not know about this classic buddy-cop action movie.
1. Mel Gibson can thank Riggs for landing him the juicy lead role in 1990's "Hamlet." Director Franco Zeffirelli was impressed by Gibson's acting in the scene where Riggs considers committing suicide.

2. Most aspiring filmmakers have to work for years to get a foothold into the industry, but writer Shane Black wrote the "Lethal Weapon" screenplay shortly after graduating from UCLA and almost immediately caught the eye of producer Joel Silver. Some guys have all the luck...3. For all that his character complained about being "too old for this s***," Danny Glover was only 40-years-old when "Lethal Weapon" was filmed. No wonder Murtaugh didn't actually wind up retiring until 1997's "Lethal Weapon 4."

4. It's just as well Glover was still a spring chicken, as he and Gibson had to go through some pretty intense physical training for their roles. Both actors spent months training and studied martial arts forms like Capoeira, Brazilian jiu-jitsu. and something called "Jailhouse Rock."5. "Star Trek" icon Leonard Nimoy was approached to direct "Lethal Weapon," but he was apparently turned off by the film's violence. Instead, Nimoy went on to direct the hit comedy "Three Men and a Baby."

6. We very nearly lived in a world where Bruce Willis played Detective Riggs and Mel Gibson was the face of the "Die Hard" franchise. Willis turned down the part of Riggs to star in "Die Hard," while Gibson turned down the part of John McClane to star in "Lethal Weapon."

7. Willis was hardly the only one to turn down the part of Riggs. Other candidates included Jeff Goldblum, Christopher Reeve, Patrick Swayze, Pierce Brosnan, and Michael Douglas.8. During the course of the movie, Murtaugh tells Riggs a story about surviving a battle in Ia Drang Valley during the Vietnam War. Funnily enough, Mel Gibson would eventually go on to star in 2002's "We Were Soldiers," which depicts that particular battle (above).
9. The film once featured completely different opening and ending scenes. Originally, the movie ended with Riggs and Murtaugh bidding farewell rather than Riggs showing up for Christmas dinner at the Murtaugh household.

10. Riggs is very good at cheating death. An earlier draft of the script had Riggs dying at the end, and Black also contemplated killing off the character in 1989's "Lethal Weapon 2."11. While we'll probably never see a "Lethal Weapon 5," now that the franchise has been rebooted for TV, Shane Black apparently did write a story for a new sequel. In an interview with Nerdist's The Writer's Panel podcast, Black revealed that he co-wrote a 62-page treatment that would reunite the iconic cops in what the filmmaker thought would make for a "very good movie."

"It was essentially an older Riggs and Murtagh in New York City during the worst blizzard in east coast history, fighting a team of expert Blackwater guys from Afghanistan that's smuggling antiquities," Black said. "And we had a young character that actually counter-pointed them."

So why did the movie not happen? "I didn't wanna do what people do when they're trying to transition which is, they sorta put the two older guys in the movie, but really it's about their son!" Black said. "And he's gonna take over and we're gonna do a spinoff. F**k that, if they're gonna be in the movie, they're gonna be in the movie -- I don't care how old they are."