Corrected entry: Look at the dress uniforms they wear after the battle scene. They are Marines in their dress green uniform but it looks like the Army dress greens. Marines wear their rank and stripes on the sleeves in red.
Corrected entry: The premise of the movie was that a critical mass of Arabs were shooting at the embassy, which justified Jackson's decision to fire indiscriminately on the crowd. However, afterwards the camera scans over the bodies and not one weapon can be seen. Pause it and look for yourself. Did everyone manage to fall on top of their weapons as a last act before death?