According to Penny Marshall's memoir "My Mother Was Nuts", the part of Sergeant Cass was originally offered to Ving Rhames. He turned it down, as a friend (Quentin Tarantino) had written a part for him specifically, in Pulp Fiction. When he turned the role down, it was offered to Gregory Hines. Penny Marshall's only concern was that Gregory Hines was too nice. Even when he was yelling at the troops, he came off as nice.
Throughout the movie, the recruits treat Private Haywood (Mark Wahlberg) as if he has no rhythm, leaving him out of their rap song, and making fun of him when he is trying to keep a beat on the desk. In real-life, Mark Wahlberg was a professional rapper.
After failing to bring in audiences as a comedy under the original title "Renaissance Man", the movie was re-released to theaters a couple months later marketed as a drama with the alternate title "By The Book", and unsurprisingly pulled in far fewer receipts the second time through the theaters.
Scenes of the fictional "Fort McClane, Michigan" were filmed at Fort Jackson, South Carolina. Landmarks, the post's motto "Victory Starts Here", and the distinctive unit insignia of Fort Jackson, all reveal the true identity of the base.
Screenwriter Jim Burnstein and his family can be seen behind Danny DeVito, when Bill Rago and his daughter are at the Tigers game. To the right of Mr. Burnstein, are his son Gabe, daughter Devon, and his wife. Usually, Mr. Burnstein and Gabe are the only ones visible on-screen.
With one minor omission, Private Benitez recites the St. Crispin's speech from Henry V perfectly. The actual speech goes "For he today that sheds his blood with me, shall be my brother, be he ne'er so vile. This day shall gentle his condition. And gentlemen in England...", whereas Private Benitez recites it as "shall be my brother. And gentlemen in England..."
About halfway through the movie, when Bill Rago (Danny DeVito) is in Colonel James' (Cliff Robertson's) office, you can see a red patch on the far right in the background. This is a Ragin' Bull Six patch from the United States Air Force Academy.