Here's how Rambo: First Blood Part II was nearly a buddy comedy between Sylvester Stallone and John Travolta. Despite the success of the first two Rocky movies, Sylvester Stallone had trouble landing a hit movie outside of the franchise until he accepted the lead in First Blood. This cast him as John Rambo, a Vietnam vet suffering from PTSD who launches a one-man war on a small town after being abused by an arrogant sheriff and his deputies. The movie had spent years in development hell where everyone from Steve McQueen to Dustin Hoffman had passed on the lead.
First Blood proved to be a surprise success, and Stallone returned to the role a further four times in the years that followed. While the first entry is a relatively grounded survival thriller, by the time Rambo III came around the character was basically taking on entire armies by himself. The most recent instalment was 2019's Rambo: Last Blood, which saw the aging soldier taking revenge against the Mexican cartel that kidnapped his friend's daughter. The sequel ended up received mixing reviews and was a box-office letdown.
Rambo: First Blood Part II from 1985 saw the character being released from prison and sent back to Vietnam to scout for evidence of POW camps. The sequel seriously dialed up the action quota compared to the original and gave Stallone a chance to show off his impressive physique. In many ways, the sequel would come to define the action movies of the 1980s but something even fans of the series tend to forget is it was co-written by James Cameron, who took on the assignment while getting ready to shoot The Terminator. While the broad strokes of Cameron's script are similar to the final movie, Stallone ended up rewriting quite a lot of it, including dropping a comedy supporting character earmarked for John Travolta.
This may sound like an unlikely pairing, but Sylvester Stallone had just recently directed Travolta in 1983's Staying Alive, a sequel to Saturday Night Fever. In the script, Rambo was to be accompanied in the field by Lieutenant Brewer and producers thought Travolta would be perfect for the role. Brewer was to be a much more tech-savvy and wisecracking character, which of course provided a comic contrast with Rambo, who would bristle at his partner's shenanigans. That said, the two would eventually bond and Rambo would have to rescue Brewer from the POW camp in the finale.
The decision was ultimately made to drop Brewer from Rambo: First Blood Part II, with the filmmakers feeling the focus should be on the title character. The basic story didn't change much when Brewer was removed either, so the movie didn't really hurt for his absence. While the buddy comedy pairing of Stallone and Travolta would have been an intriguing dynamic - to say the least - it probably worked out for the best.