A good timeline is posted here . I still haven't processed it fully yet, but the idea that Aaron brought two boxes back with him starts making sense. The original failsafe box has to be moved to somewhere else, because Aaron is still in it. He has to also get an additional box to replace the original failsafe, because Abe is expecting it there (and empty) - and indeed uses it later on to go back himself. The third box is necessary for Aaron to be able to privately go back (potentially a few times) to refine the "party intervention" until he's satisfied with it. He needs the additional box because all the other ones are in the other timelines and are already "in use". OK, melts your brain. Read More...