The Russian made RPG 7 used to fire on the U.N. aid convoy has no warhead on it. As such it would be unable to fire.
Almost all uniforms, insignia, military equipment, weapons and vehicles of the Bosnian Serb Army shown in the movie, are completely inaccurate and never seen in the war in the former Yugoslavia. Whilst some wardrobe pieces (e.g. ranks and insignia) are fully imaginary items, most other military props are obviously of non-local origin (mostly came from former Soviet Block armies, notably Hungary, where most of the filming took place). Practically all of the shown 'Bosnian Serb' distinctive sleeve insignia, are actually from the surplus of The Federal Republic of Yugoslavia Army and were, as such, never worn by Serbs in the Bosnian War.