Trivia

The cue ring, or dot (usually referred to as a "cigarette burn"), which indicates to the projectionist it's time to change the reel, is green, instead of its usual black color.

Unfortunately for the film's director, Joseph Losey, the eccentric, politically conservative Howard Hughes took over RKO while this film was being shot and, hating the film's pacifist message, did his best to sabotage it. Losey, however, managed to protect the integrity of his project. Screenwriter Ben Barzman, who was also later blacklisted along with Losey, would later recall that "Joe shot the picture in such a way that there wasn't much possibility for change. A few lines were stuck in here and there to soften the message, but that was about it." Barzman also remembered that 12-year-old Dean Stockwell was called into Hughes' office, and Hughes told him that when the other children spoke of the horror of war, he should say, "And that's why America has gotta have the biggest army, and the biggest navy, and the biggest air force in the world!" According to Barzman, little Stockwell was so in sympathy with the film's message that he dared to respond, "No, sir!" Even after Hughes started to scream at him, the boy held his ground and refused to do it. Dean Stockwell later played Howard Hughes in Tucker: The Man and His Dream (1988).

Dean Stockwell and Russ Tamblyn met each other for the first time on this film, and became life-long friends. They subsequently appeared together in The Last Movie (1971), Human Highway (1982), Win, Place or Steal (1974), and Thou Shalt Not... - February 2, 1974 (1989). Stockwell also appeared in Blue Velvet (1986) and Dune (1984) for director David Lynch. Tamblyn credited Stockwell with introducing him to Lynch as well, which is how he managed to land his comeback role on Twin Peaks (1990).

Dean Stockwell was allergic to the green wig he had to wear and became ill because of it.

Gary Gray was originally cast in the role of Peter Fry, but he contracted chicken pox and was replaced by Dean Stockwell.