When Gomer and Carter return to the base, they're supposed to have been gone on a five-day wilderness survival test. Yet, both men are visibly clean shaven. Surely, they wouldn't have brought shaving supplies with them on a survival test.
When they're done eating the wild pheasant both Carter and Gomer carelessly toss the bones over their shoulders. An experienced Marine and a "country boy" skilled at living off the land would know to never leave waste materials like that improperly disposed of. It is unsanitary and attracts vermin and insects plus, in an actual combat situation, it gives patrolling enemy units clues to your presence and direction of travel even after you've moved on.