The ammo belts around each soldier's waist were empty. The rifles never ran out of ammunition.
At the water hole after Sgt. Vinson jumps off the rock to take out the sentry, as they are rolling down the sandy hill, you get a great shot of the stunt man's white briefs as his breech-cloth is flapping in the struggle.
Forrest Tucker's Irish accent constantly comes and goes throughout the movie.