In the first part of the movie, in the sequences inside the barracks during the drill, a special lens was designed to keep every single Recruit in focus. Director Stanley Kubrick intended that no one was special and they all had the same treatment.
To make Gunnery Sgt. Hartmann's performance and the recruits' reactions as convincing as possible, Matthew Modine, Vincent D'Onofrio, and the other actors playing recruits never met R. Lee Ermey prior to filming. Stanley Kubrick also saw to it that Ermey didn't fraternize with the actors between takes.
Director Stanley Kubrick had nothing but praise for R. Lee Ermey's skills as a performer. Kubrick originally was going to write dialogue for Ermey's character himself, but he became so impressed with what Ermey improvised, he decided it was not necessary. He simply let him ad-lib, an act practically unheard of for a Stanley Kubrick film. Ermey's performances were so faultless that Kubrick only needed two to three takes to get his scenes filmed, which was also extremely rare for a Kubrick film. The only instance Ermey had to film more than two to three takes was in the "Jelly Doughnut Scene," which he claimed was filmed in 37 takes, to the point his voice kept disappearing from time to time.
In an interview for the DVD, R. Lee Ermey said he felt Vincent D'Onofrio's performance was not only the best in the film, but the best part of the film as a whole.
According to an interview with Vincent D'Onofrio, the production schedule for the film was so drawn-out that lead actor Matthew Modine got married, conceived a child with his wife, the child was born, and then turned 1 year old...all during the course of filming.
Vivian Kubrick: Stanley Kubrick's daughter makes a cameo appearance during a scene in Vietnam where Joker and Rafterman encounter a mass open grave. She can be seen wielding a motion picture camera, shooting into the open grave for a few moments. Vivian Kubrick was also the film's composer, credited as Abigal Mead. According to her, the name was based on Abbott's Mead, the mansion where the Kubricks lived from 1965 to 1979. It was located near to MGM's Borehamwood studio.
Stanley Kubrick: Cowboy uses the radio to communicate with his superiors (aka: "Hotel"), requesting a tank be brought in for support. The voice of "Hotel" is non other than Kubrick himself.
Stanley Kubrick: [Kubrick stare] Pvt. Pyle (Vincent D'Onofrio) has the 'Kubrick stare' during the scene in the bathroom, where his head is tilted down slightly while the eyes look up.
Stanley Kubrick: [credits] Except for the title cards "A Stanley Kubrick Film" and "Full Metal Jacket", there are no opening credits.
Stanley Kubrick: [Bathroom] Crucial scenes of the first act, including its shocking climax, take place in the "head" of the barracks.
Stanley Kubrick: [faces] Private Pyle during the scene when all Marines are being pumped up to kill, and when he is in the head.