I think it is possible that the bomb did not go off, but there was definitely a flash and that flash was another time jump. Maybe Ellie went to the wheel and turned it before Juliet was able to set off the bomb and that made her appear in Tanzania like the others that moved the wheel. This would also explain how Widmore would have become the next Leader of the Others.
Or maybe the death of Jacob caused the flash before the bomb was activated and this reset everyone to their correct time.
Anyhow I think it was a time flash.... not the bomb at all.
One last observance: If Ellie did turn the wheel and appeared in Tanzania, she will have the completed journal of Daniel's with her. So, when she gives it to him next time it will be completed instead of blank!!!