Missing in Action 2: The Beginning (1985)

Revealing mistake: At the beginning of the film when Nester and Opelka and at least two other Americans are attempting to run towards the chopper, you hear a series of Vietnamese mortars which hit two of the Americans, followed by screams. If you look real closely at the last mortar to hit the second American, it is a scare-crow type figure dressed in military fatigues that takes the mortar hit.