Rambo was banned in Myanmar (formally Burma), and bootlegs are a hot item. Burmese Freedom Fighters have even adopted dialogue from the movie as battle cries, most notably "Live for nothing, or die for something." Sylvester Stallone said "That, to me, is one of the proudest moments I've ever had in film."
Sylvester Stallone specifically wanted the film to be set in the midst of the most brutal ongoing global conflict that was basically ignored by the public and media. After ruling out established (and well-known) conflicts in the Middle East, Latin America and Africa, Stallone talked to international experts who told him about the Burmese junta's mass murder of the Karen people. He then set the movie's storyline in the middle of this genocide.
Rambo's knife in this film is a primitively built golok made out of a slab of metal as opposed to his expertly crafted survival knives in the other films. Sylvester Stallone actually stayed up all night filming the scene of him forging the knife like you see in the film, although due to time constrictions, he had to do it all at once without cooling the blade. They went through about seven pairs of heat protective gloves due to this. Sly claims after making the knife, he had a rather warm handshake.
The first Rambo film where Rambo uses a pistol. Also the first Rambo film without a helicopter. Most notably, it is the first Rambo film completely without a scene in which John Rambo is without his T-shirt, showing his muscles. This is due to Sylvester Stallone's, extensive tattoo work on both shoulders, which he started getting in late July 2007.
Originally, Rambo was supposed to hold the M2 .50 caliber machine gun in his hands and fire it, but when fully assembled the .50 weighed 120 lbs. Stallone was still capable of holding and firing it but it was too cumbersome for quick movements, so they mounted it on the back of a jeep instead.
James Brolin was attached to play the Col. Samuel Trautman role after Richard Crenna died of pancreatic cancer in 2003, but the role was written out of the script. Sylvester Stallone considers the character to have died on the same day as Crenna, who appears in an archival flashback in Rambo (2008).
Many critics and audience members felt that the horrific wounds inflicted by the M2 .50 caliber heavy machine gun in the finale were so gory that it was unrealistic. Returning Iraq and Afghanistan veterans who had recently used the M2 in combat noted that the wounds were quite accurate, and if anything, toned down from reality. In the audio commentary on the DVD & Blu-ray versions of the Stallone himself makes note of this fact.
In his commentary for First Blood author David Morell cites the inspiration for John Rambo as being World War 2 hero and later Hollywood actor Audie Murphy. Rambo's last stand in the finale is very similar to how Murphy was awarded the Medal of Honour [sic], manning a vehicle mounted 50. calibre [sic] machine gun and singlehandedly holding off hundreds of enemy soldiers.
In many countries, the first installment, First Blood (1982) was re-titled "Rambo", so the title for the fourth installment had to be changed accordingly. In several countries, including France and Germany, the film is called "John Rambo." In Russia, the film is called "Rambo 4."
During its long development process, 'Rambo' went through a number of story premises. One un-produced script featured Rambo living a quiet life with wife and child, until white supremacists kidnap his family. Another script found Rambo trying to stop a hostage situation at the United Nations, where he is working as a diplomat, when terrorists (including Rambo's adopted son) take hold of the UN headquarters in New York.
Rambo is addressed as "boatman" during the movie. From Greek mythology, "Charon" (the boatman) ferried souls to the land of the dead for money. Burma/Myanmar, with a 60+ year civil war and genocide, qualifies as the land of the dead. Also, the name of the rebel faction is "Karen" which is pronounced like "Charon".
During the montage after Rambo is asked to transport the mercenaries, it shows the alternate ending to First Blood (1982) where Col. Trautman (Richard Crenna) would have ended Rambo's revenge on Teasle by shooting him in the abdomen.
This is the first Rambo film without a companion novel by David Morrell, Rambo's creator. Morell wrote the novel "First Blood", the basis for the first Rambo film, and novelizations of 'Rambo: First Blood Part II' and 'Rambo III'.
The first Rambo film to depict Rambo fabricating his knife/machete. Rambo III had a scene of Rambo forging his own knife, although not in the film itself, it is in the deleted scenes of the Ultimate Cut DVD.
The first film where Rambo does not acquire an enemy vehicle of some kind. In First Blood, Rambo commandeers a deuce and a half cargo truck. In Rambo: First Blood Part II, Rambo assumes control of a enemies' UH-1 helicopter. Rambo III features Rambo requisitions a Soviet Tank. While he mans the .50 heavy machine gun in Rambo, he does not pilot the vehicle.
Thus far, First Blood and Rambo: First Blood Part II both feature bowies produced by Jimmy Lile, where Rambo III and Rambo feature a bowie and machete respectively. Both were produced by renowned fantasy knife-smith, Gil Hibben.