Weapons coordinator Robert "Rock" Galotti amassed over 500 vintage World War II-era firing weapons and 700 rubber replica weapons for the film from private collectors and prop houses. Also featured moving across battlefields are vintage Sherman tanks, their smaller Stuart brethren, and Japanese Hago tanks.
Roger Willie was originally hired as a Navajo dialect coach. His screen tests were so good, he ended up cast opposite Christian Slater.
To add authenticity, MGM bought some genuine World War II-vintage radios from Samuel M. Hevener, a collector from Ohio.
The film was intended to be John Woo's dramatic breakout film for a major studio, and a lot of effort was put into hiring the right people to invoke his vision, including Oscar winner James Horner. However, the studio saw it as a war-time action film and forced Woo to re-edit it. The result was total disaster for the studio, losing over $70 million.
Prior to filming, most of the principal cast joined a core group of 62 extras for boot camp, where they endured a week of rigorous military training as World War II Marines. The production received assistance from the Department of Defense, which made Kaneohe Marine Corps Base available for the actor's basic training. Under the tutelage of Sergeant Major James D. Dever (a retired 25-year veteran of the Marine Corps) and his active-duty Marine instructors, the cast learned how to walk, talk, and think like Marines.