A total of 50,000 rounds of ammunition, 300 pounds of TNT, 600 pounds of blasting powder and ten cases of 40% dynamite were required for the filming of the battle scenes.
Audie Murphy originally declined the opportunity to portray himself in the movie, not wanting people to think he was attempting to cash in on his role as a war hero. Murphy initially suggested his friend Tony Curtis to play him. They had worked together on three westerns--Sierra (1950), Kansas Raiders (1950) and The Cimarron Kid (1952).
Audie Murphy's war buddy Onclo Airheart was slated to play himself, but he declined due to the fact the film was to be shot during planting season.
In the DVD commentary for First Blood (1982) author David Morell cites Audie Murphy as the inspiration for the character of John Rambo. In the final Rambo film (Rambo (2008)) he takes on hundreds of enemy soldiers with a .50-cal machine gun mounted on a vehicle, just as Audie Murphy does at the end of this film (and as he actually did during the battle).
Audie Murphy was the most decorated US soldier of World War II. According to this film, when he applied for service with the Navy, the Marines and the Army he was turned down by all three branches. Moreover, when he joined his combat unit, one of his superiors considered transferring him out of the company for being unfit for combat.