- Backed by the Pentagon: After John Wayne bought out Robin Moore, the original author's, share in the production. The Pentagon was trying to prosecute him for revealing classified information.
- California Doubling: Fort Benning, Georgia, stands in for both Vietnam and Fort Bragg, North Carolina. Those soldiers exercising on the field when Kirby calls out to them were real soldiers going through Airborne School (located in Benning) at the time.
- Cast the Expert: The colonel who ran the jump school (and who was seen shooting trap with Col. Kirby) was the real jump school commandant and a legendary commander of U.S. paratroopers.
- Dawson Casting: Most colonels were only in their 30s during The Vietnam War. John Wayne, playing a colonel, was 60 when this film was made and Bruce Cabot, also playing a colonel, was 63.
- Deleted Role: Scenes were filmed with Vera Miles as Col. Kirby's wife but they were cut before release by the studio. The scene only took one morning to shoot, but the film was considered overlong, and that scene was judged easiest to cut. Batjac, John Wayne's company, offered her 10,000 dollars for her work. When she refused that, they then offered her a new car, which she also declined to accept. Wayne made up for this by casting Miles in his next film Hellfighters.
- Doing It for the Art: John Wayne helped to personally bankroll the movie and turned down the role of Major Reisman in The Dirty Dozen in order to co-direct and star in it. He claimed that his goal was not to make a political film, but a tribute to the courage of the American soldier and Special Forces specifically.
- Executive Meddling: The Pentagon requested edits to the script so that it showed the South Vietnamese as a bigger part of the war effort, and changed the abduction of the North Vietnamese general, which originally featured a cross-border raid into North Vietnamnote .
- Fake Nationality: The Vietnamese characters were played by Japanese actors.
- Hostility on the Set:
- John Wayne and Aldo Ray did not get along during filming. Ray later spoke disparagingly of Wayne in interviews.
- David Janssen had a severe argument with Wayne on the set of the production because Wayne lost his temper on a young Asian actor during the shooting. Janssen left the set, which he never did before in his career.
- Old Shame: George Takei has admitted in interviews that while he was grateful to be cast in this film, he nevertheless strongly disagreed with the film's pro-war message and felt the finished movie was very bad.
- What Could Have Been: John Wayne wanted his friend Elmer Bernstein to score the film but Bernstein felt compelled to turn the opportunity down, as he didn't feel it sat well with his politics.
Trivia / The Green Berets