The camouflage uniforms worn by the American raiders are not WWII military camouflage uniforms. They are wearing commercial duck hunter suits that were sold in the USA after World War II. They are based on wartime USMC camouflage uniforms and bear a passing resemblance.
In the final battle, the closeups of the machine gun showed U.S. .30-06 ceremonial blanks, with red wads in the cartridge, in the ammunition belt while firing. When the gun was at rest, ball rounds, with projectiles in the cases, were in the belt.