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 WWII 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 Sgt. Maj. 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.
Nicolas Cage actually learned to speak Najavo fluently for his part despite the fact that his character in the film does not. Cage later said that he did it to better understand the script but John Woo maintained that Cage had misunderstood which character he had been cast in.
Weapons coordinator Robert 'Rock' Galotti amassed over 500 vintage WWII 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.
George Smith, one of the Navajo code talkers who helped the U.S. military outfox the Japanese during World War II by sending messages in their obscure language, has died, the president of the Navajo Nation said on 2 November 2012.
When the film release was pushed back, many of the posters/cutouts/promotional items/etc. sent to theatres were recalled. As such, they have become collector items and fetch huge prices on auction sites like eBay.
Steve J. Termath was originally cast for the role of Pvt. Nellie. However, the role went to Martin Henderson when Termath took a brief hiatus from acting for actual military service, enlisting in the US Army Reserves.
The Desert scene in the opening credits is Monument Valley, Utah used in movies such as Back to the Future Part III (1990), National Lampoons Vacation, and City Slickers II: The Legend of Curly's Gold (1994).
During the "Blue Bus" Scene at the Beginning, they originally had a person riding a horse around the trading post. But, somehow the Horse got spooked, bucked off the rider and ran around "frantic" around the set, crew, cast, extras and cameras at Vasquez Rocks Park in Los Angeles county. They finally caught the horse and it was cut out of the scene immediately.
In the Camp Tarawa scene, while Ox Henderson (Christian Slater) is running with Joe Enders (Nicholas Cage), Ox tells Joe that people call him "Ox" because he is from Oxnard, California. This scene was filmed at Naval Air Station Pt. Mugu which is just a few miles away from the actual city of Oxnard, California.