The film was mostly shot in Bangkok, Thailand, and at the time, several hundred male students from the International (American) School of Bangkok (ISB) were recruited as extras to perform in the multitude of shots showing American GI's throughout the film. As a courtesy, Robin Williams actually came to ISB and put on a stand up routine for all students in the 10th grade and above.
The script went through several revisions after it was originally drafted by Adrian Cronauer in 1979. Cronauer first pitched it as a TV series, then a Movie-of-the-Week. It was the latter treatment that landed in the lap of Robin Williams, who realized the DJ role would be the perfect outlet for his brand of comedy. The original treatment by Cronauer was completely re-tooled for Williams.
During one of his improvised news broadcasts Robin Williams brings up Hanoi Hannah, calling her the "wicked witch of the north". Hanoi Hannah was the stage name adopted by Trinh Thi Ngo, a North Vietnamese female broadcaster who was made famous on both sides of the war for her thrice daily North Vietnamese English language propaganda broadcasts. While her carefully scripted broadcasts were intended to taunt and demoralize American troops, Hannah's broadcasts, containing misused American slang, bizarre cultural references, mispronounced words, and outrageous claims of imaginary NV victories were largely considered among GIs as a source of ridiculous entertainment.
Robin Williams's portrayal of Adrian Cronauer has led to confusion as to the beliefs of the real Cronauer. Cronauer has said that the film is about 45 percent accurate, according to a biography on Robin Williams. Cronauer has said that the film misrepresented him to make him seem anti-war, when he was, in his own words, "anti-stupidity." In fact, Cronauer - who later became a lawyer, and died in 2018 - became an active Republican and was a vice-chairman of the 2004 Bush-Cheney re-election campaign. Furthermore, Cronauer has also said that if he'd done half the things Williams did in the film, he would've been court-martialed and sent to Fort Leavenworth.
Barry Levinson: [Ralph Tabakin] (Chaplain Noel) Ralph has appeared in every Levinson picture from Diner (1982) to Liberty Heights (1999).