In Mission 6, a patrol boat appears with the helmsman offering to pick the team up. There is no one else aboard this patrol boat, which would never happen especially in Viet Nam.
The CAR-15 is referred to as a sub-machine gun; it is, in fact, a carbine.
The rates of fire of all the weapons are incorrect.
Staff Sergeant Weir is tasked with clearing a village. After being given his orders, he reloads his submachine gun. Since he hadn't fired it before on the mission he was on, it makes no sense that he should reload his weapon since it would already be fully loaded.
The tracer on the M-60 machine gun is to the right of the front sight. Since the sight on the M-60 is centrally mounted, the tracer should also appear from the Center.