Co-writer James Cameron claims that he only wrote the first draft of the script and that Sylvester Stallone made many changes to it. When the film was released, the "political" content of the movie was considered controversial. Many felt the Vietnam conflict was "altered" to look and sound heroic. Cameron commented that he only wrote the "action" and that Stallone wrote the "politics".
James Cameron's original screenplay began with Col. Trautman finding Rambo in a psychiatric hospital instead of a prison. The psychiatric hospital concept was instead depicted in Terminator 2: Judgment Day (1991).
Rambo's stats, as given in the film: "Rambo, John J., born 7/6/47 Bowie, Arizona of Indian-German descent. Joined army 8/6/64. Accepted, Special Forces specialization, light weapons, cross-trained as medic. Helicopter and language qualified, 59 confirmed kills, two Silver Stars, four Bronze, four Purple Hearts, Distinguished Service Cross, Congressional Medal of Honor."
According to the documentary We Get to Win This Time (2002), the producers considered teaming up Sylvester Stallone with his Staying Alive (1983) protégé John Travolta (who was once considered to play Rambo himself in the first film) as Rambo's young partner in rescuing the American POWs. Stallone nixed this idea when he decided it would be better to make the film a solo project.
The huge Buddha statue that was used in the opening sequence was given to the local Mexican military commander as a souvenir after the shoot, even when he was told it's just a prop made from expanded polystyrene and a lot of gold paint.
In First Blood (1982), Col. Trautman's Green Beret flash is that of the Army's 5th Special Forces Group. In this movie and the sequel (Rambo III (1988)), he is shown wearing the flash of the 1st Special Operations Command, which means he was reassigned after the events of First Blood.
The only movie in the Rambo/First Blood franchise in which Rambo shares an intimate kiss with a woman (the female agent Co). In _First Blood (1982)_ there were flashback scenes of Rambo at a Saigon bar kissing and making love to a Vietnamese prostitute, but those scenes never made it into the final cut of that film.
All of the shots on the military base were done on a Mexican air force airstrip. The logos have been painted over or obscured, and the real crew always have their backs toward the camera or are far enough away from the camera so no one would notice.
The Mi-24 Hind-D helicopters seen in the film are in fact modified Aerospatiale SA 330 Puma transport helicopters with fabricated bolt-on wings similar to the real Hind-Ds used in the former Soviet bloc nations.
The trivia items below may give away important plot points.
As Co Bao (Julia Nickson) died in Rambo's arms after the ambush, there was supposed to be a triple zoom-in while Sylvester Stallone screams "No!" echoed 3 times. During a test screening, audience actually started laughing. It was quickly re-edited to the present form.
In a rare alternate take of the ending scene (when Rambo says, "I want, what they want, and every other guy who came over here and spilled his guts and gave everything he had, wants! For our country to love us as much as we love it! That's what I want!"), Rambo wept as he told this to Trautman. A behind-the-scenes video of this take can be seen in an episode of Entertainment Tonight (1981) from the mid-to-late 80s.