The "behind-enemy-lines-rescue" is a reliable plot but it fails here largely because the movie doesn't seem to know what point it's trying to make. Having U.S. Air Force pilots dropping gas-bombs on innocent civilians would seem to position the movie as a condemnation of American involvement in Vietnam. However, showing those Vietnamese fighting against the Americans to be commanded by brutes who rape and torture and kill helpless prisoners blurs the line between "good guys" and "bad guys." The audience is left with no one to root for, (especially since none of the characters is of any interest or value), and the movie is written in too shallow a way to allow it to claim to be "dark" or "cynical." Making things worse is the movie's tendency to pad its footage with extended and unnecessary scenes, such as all those shots of characters trudging through the jungle accompanied by monotonous music.
This movie has acquired a cult reputation, however, because of a scene from it posted on YouTube. This scene shows the torture of the two captured USAF pilots. These pilots - young, hairy, attractive, and soaked with sweat - are only seen from the waist up but apparently they've been stripped naked and apparently they're being subjected to electric shocks delivered directly to their genitals. It's rare that the movies show or even imply genital torture. It's also rare to show manly torture victims screaming at the top of their lungs as these two pilots do. (They're played by Jim Dixon and Bernard Higgins.) Compare this scene to a similar one in "Rambo 2." Sylvester Stallone is also subjected to electroshock torture but he's allowed to keep his pants on, thus putting his genitals "off-limits." He also doesn't lower himself by screaming but instead allows himself only a few grunts of discomfort. Needless to say, the torture scene in "Assault Platoon" is far more convincing, far more memorable.