Bandage missing from Vietnamese girl's right wrist right after the underground bunker was destroyed by bombing.
In the movie, Michael Pare's character is referred to as Lieutenant but the credits show him as Sergeant.
The small American base camp depicted is set in heavy jungle terrain without the ability to see it's own perimeters. This would be fine if this was during WWII in the Pacific, to hide from Japanese aircraft. But in Vietnam the jungle would have been cleared with "kill zones" in place for camp defenders. Outer and inner multiple barbed wire fences would be around the perimeter of the camp. This defensive construction strategy would prevent such a surprise invasion attack as portrayed in the film.
On the cover for the movie there is a black hawk helicopter where it should have been a Huey UH-1H.
In various scenes we can see soldiers equipped with M16A2 assault rifles. This is an obvious mistake, as M16A2 variant was introduced in the 1980s and not even single one was used during Vietnam War.
According to the 1968 year depicted in the movie, soldiers should be wearing slant pocket jackets and pants.