Yeah, I see it, but whatever hit him would probably be moving too fast to see. On the other hand, he could have just got the wind sucked out of him from the blast. He could have been close to collapsing without the explosion.
If it were part of the actual bomb, certainly.
If it were, say, a cell phone blown out of the hand of a nearby spectator, maybe not.
In any event, it sure looks like something smacked him.