The title "Lethal Weapon" was inspired by a nickname given to Mel Gibson's character, Martin Riggs, by a member of the Special Weapons and Tactics (SWAT) team during a standoff in the first movie. The TV series that followed in 2016 also used the same title as a nod to the original films.

Inspired by Real-Life Events: The character of Martin Riggs was partially inspired by a real-life Los Angeles Police Department officer named Gene Klein. Klein was known for his fearless approach to dangerous situations and also tragically lost his wife in a car accident, much like Riggs in the movie.

"Lethal Weapon" Influence on "Die Hard": The success of "Lethal Weapon" played a role in influencing the creation of the "Die Hard" franchise. The "Die Hard" series, starring Bruce Willis as John McClane, also became a prominent action movie franchise of the late 1980s and '90s.

Recurring Supporting Characters: Actor Steve Kahan played Captain Ed Murphy in all four "Lethal Weapon" movies. He was the only actor, other than the main leads, to appear in each installment of the series.

Glover's Fear of Guns: Danny Glover, who played Roger Murtaugh, had a fear of firearms before taking on the role in the first movie. He had to undergo extensive training to convincingly portray a police officer.

Alternate Casting: Several well-known actors were considered for the role of Roger Murtaugh before Danny Glover was cast. These actors included Sidney Poitier, Bill Cosby, and Gregory Peck.

Shane Black Connection: The screenplay for the first "Lethal Weapon" film was written by Shane Black. He was initially paid $250,000 for his script, which was a record-breaking amount for an unproduced screenplay at the time. Shane Black also played a small role as a driver in the first movie.

Riggs' Name Origins: Martin Riggs' first name is an homage to George Martin, the producer of The Beatles, whom Mel Gibson admired. Riggs' last name comes from the character Ethan Edwards, played by John Wayne in the classic Western film "The Searchers."

Riggs' Desert Eagle: Martin Riggs's iconic firearm in the movies is a Desert Eagle .50 caliber handgun. The weapon became synonymous with the character and is often associated with the "Lethal Weapon" franchise.

Joe Pesci's Improvisation: Joe Pesci's character Leo Getz became known for his fast-talking and comedic moments. Many of his lines were improvised by Pesci, which added a unique charm to the character.

The "Lethal Weapon" film franchise has left a lasting impact on the action genre and remains beloved by fans worldwide. These curious facts add to the rich history and behind-the-scenes stories of the series.