At the Battle of Khe Sanh, you're told to clear the trenches. What is missed by most is a nearly inaudible clue telling you that there are barrels full of napalm. And, more importantly, there's no help in telling you what to do with those barrels. Shooting them does nothing. Neither does trying to clear the trenches with one of the mounted machineguns, as the Viet Cong keep pouring out in an endless wave. Nope, you have to run to two of the giant, striped barrels near the bottom of the hill and kick them down into the trench. There are two of them. Hide behind the sandbags and take shots at the VC until it's relatively clear. Make a run for the nearby barrel and use the prompt to stab it and kick it down the hill.