An idea that has been rolling about in my head for a while...
So for whatever reason, the Enola Gay has some kind of engine trouble and is going to crash. The crew heroically dive the bomber into the target zone of "Little Boy" and perish (of course). Due to the design of the bomb, it's still going to detonate.
Surely to hell there are some sort of butterflies to using the kamakaze tactic against the Japanese (even if by accidental necessity), but I figured you folks would have more to say about this than I.
So, what if Hiroshima had been a suicide mission? Cultural butterflies at least?