Conover, the door gunner on the Army Huey with Doc Jardian, was wearing a unit patch for the 173rd Airborne Brigade (Army), but was mentioned posthumously as "Lance Corporal Conover". Lance Corporal is a Marine (USMC) rank, not an Army rank.
Commander Markel, Lane Smith, refuses to let Jardian transport a critical patient on a multi- million dollar transport aircraft. The actual aircraft is a WWII era C-47 with $185000 in 1967-1968.
Lt. Don Jardian (Ken Wahl) is seen saluting a superior officer while uncovered (with his cap or hat removed). Naval services do not salute while uncovered. Later, he is seen covered (wearing his uniform cap) while visiting nurse Deborah Solomon (Cheryl Ladd) in sick bay. Naval service personnel remove their covers indoors and are particularly forbidden to wear them in sick bay or a chow hall.
In the opening scene Gunny (Lee Ermy) can be heard giving instructions to his men and a new Lieutenant on a UH1 (Huey) helicopter as it lands in a rice paddy with two or three others. There'd be little point in trying to speak to someone on a Huey in flight. The noise anywhere near a Huey is so loud you can't hear yourself speak let alone anyone else.