Continuity mistake: In the opening scene, Gunnery Sgt. Hartman is making his speech and passes by Privates Cowboy and Joker on his way to the other side of the barracks. On his way he passes Private Pyle standing to the right of Private Joker. Later in the scene, when he rushes over to confront Private Joker and then moves on to Private Cowboy and then Private Pyle, Private Pyle is on the left of Private Joker.
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: Ermey was convinced that the scenes in boot camp wouldn't be believable unless the actors were actually frightened of him. According to the commentary on the blu-ray, when he was acting as the technical adviser and training them to drill, or whatever he was training them to do, he never raised his voice. As soon as the camera was rolling, he started screaming at the actors. Much to Ermey's pleasure, the fear you see on the screen is real. Many times in the shooting the actors would become so flustered by Ermey that they would blow their lines. Ermey recalls that he's seen the other actors in the film around Hollywood from time to time, and they still won't speak to him.
Trivia: Many of the extras in the boot camp scenes were actually serving members in the British Territorial Army. They were chosen because it was assumed that they would be familiar with drill. However the English drill practices were so different from the American Marine corps practices that R. Lee Ermey himself had to re-train the British troops to march in Marine Fashion. Ermey said it was twice as much work trying to re-train them than it would have been just training raw recruits.