Prior to the production of the film, the key actors -Timothy Hutton, Sean Penn, Tom Cruise and others - were required to participate in a 45-day-long period of orientation with the students of Valley Forge Military Academy. They were given uniforms, borrowed from their real life counterparts at the school and given authentic military haircuts. They slept in campus barracks and were subjected to the same rigors and hardship that all Valley Forge cadets went through. While most of the actors enjoyed and excelled at their orientation, Cruise opted to leave the training for the comforts of a nearby hotel until filming began.
Sean Penn and a handful of other actors received military horsemanship training for the scenes as the leader of the school's mounted cavalry. He later stated "It's not like riding out on a backwoods trail-The trick is to salute, control the horse, keep in step with the other riders and try not to fall off."
Tom Cruise was originally going to play a background character in the film, but director Harold Becker was so impressed by the way he conducted himself as one of the military cadets during rehearsals that he was offered the part of David Shawn. At first, Cruise refused and then was finally convinced by Becker and producer Stanley R. Jaffe play the role.
The Culver Military Academy in Culver, Indiana rejected filming at their campus when they learned of the film's ending.
More than 2000 actors auditioned for Sean Penn's role as Cadet Captain Alex Dwyer, which Penn won after being seen in a fiery performance in an off-Broadway play "Heartland" by the film's casting director Shirley Rich.