Coffman is listed as "Coffman" in the credits, but the name on his jacket is spelled "Koffman."
During the battle at the cave, one of the "dead" Japanese soldiers at the cave entrance can be seen jumping up and going back into the cave. This appears to be the same soldier who is ultimately taken prisoner and interrogated.
After Anderson sees Pretty Boy was shot dead, he stands up and shoulders his rifle under his arm, but the next camera shot shows his rifle behind his arm.
Anderson says that stuttering and migraines come from fear. He is wrong on both counts. Stuttering can be affected by fear, but brain structure plays a major role. Migranes can sometimes come from stress, but are caused by a constriction of blood vessels in the brain. They often occur without any stimuli or stress of any kind.
Sergeant Johnson, the interpreter, wears a revolver in a shoulder holster. But the gun's grips are made of bright white ivory, making him a perfect target for the Japanese, especially in low-light conditions. No real Marine would be this careless, and no superior would tolerate such a safety violation by one of his men.
During the invasion of the enemy island, several actual World War II film clips are spliced in for realism. But in these clips, the large hull numbers on two of the ships are backwards.
The pockets of the ammunition belts worn by most of the Marines who carry M1 Garand rifles are obviously empty, since they are flat. No real Marine would go into combat with an empty ammo belt.
As his platoon is approaching an enemy-held cave, Lt Anderson checks his watch and tells his men that the time is 0530 (5:30 a.m.). However, rather than being filmed near dawn and in semi-darkness, this scene and the ones immediately following are in bright daylight.
While speaking to his superiors on his walkie-talkie, Lt Anderson twice closes his conversation with "Over and out." This is incorrect. He should have said either "Over" (if he was turning the conversation over to the other speaker), or "Out" (if he was ending the talk). Interestingly, Anderson uses the correct term "Out" later in the film.