I just thought of something remeber the pic of hiro and the dinosaur what if somehow hiro being around peter makes him remember about hiro being able to teleport back to the past so when he is about to blow up, he accitdently sends them all back in time and that is how hiro faces the dinosaur and peter blows up which then becomes the reason that dinosaurs no longer exist!
Ha. I think we all thought that at one point....but The bombs only big enough to blow up new york.