Trivia: R. Lee Ermey actually wrote all of Gunny Hartman's dialog himself. Ermey was involved in a serious car accident right before shooting, so Kubrick invited Ermey to come stay at his house in England to recover. While recovering Ermey read the script over and over, and he remarked that the Drill Instructor's dialog that was in the script was obviously the work of a screenwriter with a cliche imagination who obviously had no idea what boot camp was really like. So Kubrick allowed Ermey to re-write all of the dialog himself.
Trivia: When Jim returns home after losing his parents, his nanny slaps him. The actors had practiced a fake slap and fake reaction, but Spielberg and the actress playing the nanny conspired to make the slap real when the cameras were rolling, so Christian Bale's reaction would be genuine. Therefore, Bale is really being slapped, and his shocked reaction is no act.
Trivia: This film is based on Pentagon lawyer Adrian Cronauer's life as a DJ during the Vietnam War. He is worked in the Pentagon in its MIA/POW office until his death on July 18, 2018.