Factual error: When Petersen is first confronted by Col. Kirby for pilfering from his unit, Petersen neither comes to attention nor salutes Col Kirby (he should have done this as soon as he saw the Col.) This is such a huge breach of military courtesy, that one of the senior NCOs , if not Col. Kirby himself, would have called him on it instantly.
Revealing mistake: Except for the one that crashes, every single helicopter in this film is 100% factory fresh, brand new - no mud spatters, no scratched paint, not a dent or a blemish anywhere. They look like they just rolled off the production line. Strange that, on the front line in a war zone and all.
Factual error: After returning to camp Savoy 29, Cpt. Nimh states that he wants to go home to Hanoi but first he wants to "kill all filthy stinking cong." The civil war in Vietnam was between the Republic of South Vietnam and the Viet Cong. North Vietnam (the capitol of which is Hanoi) was a separate country that aided the Viet Cong. So even if Cpt. Nimh killed every single "filthy stinking Cong" in South Vietnam, North Vietnam would still be communist, and he still couldn't go home.
Continuity mistake: In this scene we see Muldoon giving a talk to the press. As he empties the ammo box on the desk where the press are seated we see John Wayne and another soldier in the background standing a meter apart. We then get a close up shot of Wayne and the other soldier and they are shoulder to shoulder. In the next long shot we see they are standing a meter apart.
Continuity mistake: After kidnapping the VC Commander, at one of their rest stops, Lynn is sitting, chin down but looking up. In the scene there is a large green leaf over her left shoulder from the bushes behind her. Later they take one last rest before the choppers arrive to take them. Lynn is scene sitting on a rock in the background. John Wayne looks at her and her brother in law. The scene cuts to her again and its the same clip from the previous rest period, with the same green leaf over her shoulder, but when they cut back to a long shot she is hanging her head and there is no green foliage near her.