Another plot hole? (Spoiler)
During the attack, somebody screams "RPG!", and a second later there is an explosion.
In order to spot an RPG a second (or half second) before impact, you should see where is coming from. This is almost impossible due to their speed (between 150-295 meters per second)
Let's say the soldier was able to see the RPG being charged and pointed, then he should have known where the attack was coming from.