Throughout the movie, the enlisted men and their officers salute each other, even though they're in a combat zone. This is not done in the real Army because it identifies officers as potential targets for snipers.
In the cast listing, Robert Wagner is listed as Sfc/Pvt. Sam Francis Gifford. He should be listed as T/Sgt/Pvt. Sam Francis Gifford. The rank Sfc (Sergeant First Class) did not exist during WWII. At that time it was T/Sgt (Technical Sergeant).