When captain returns to the foxhole after searching for Faulkner, he asks for a beer. There were only five to begin with, and each of the five soldiers had one.
When captain goes to retrieve Smith, Falkner has a burned but unlit cigarette between his lips in the next two shots, while in the third shot the cigarette is burning.
The Captain would have his rank visible on his helmet and uniform.
Only one of the five US soldiers has a flag on his shoulder (displayed properly, 'backwards' on his right shoulder. None of them have name plates.
Soldiers would not defy their senior officer's command and call for a vote.
A grenade does not whistle like an incoming bomb.
When Captain meets with his CO, the latter has no name plate, flags, rank or other insignia on his uniform.
Instead of saying 'another dimension,' Captain said another dimentia/dementia.