This movie is heavily touted, by Vietnam vets, in the commentary, etc, as being absolutely realistic in ever possible detail. However, there is at least one glaring mistake...

The battle starts out mentioning that the year is 1965 - the first major battle in Vietnam. So early that the standard black rifle was in it's very first production form. They were visually distinct and noted for a lack of reliability...

Throughout the movie you seldom get a good look at the M16s as they flash by so fast and are seldom noticed as anything but tools of war. However, at one point the Sgt. Major throws a rifle at Gallaway, and shortly afterward he says "Prepare to defend yourselves". Now, at this point you see a close-up of Galloway sighting down a dirty/bloody M16. There's one problem: This M16 is *not* a Vietnam-era M16, it isn't even a Vietnam-era M16A1, which was introduced in 1967. It is actually an M16A2. You can tell this due to the clearly-shown forward assist and triangular case deflector. Less obvious, but clearly visible, is the shape of the pistol grip... The forward assist was introduced in 1967, and the A2 was not introduced until the mid-1980s.