Warning: There Be Spoilers Ahead
In the Bioshock Infinite Timeline, and on multiple recordings, it is revealed, that during the events taking place after the second tear-jump (at which the Vox revolted), Elizabeth was moved to Comstock House, so DeWitt couldn't get to her. This means that in the reality taking place after the second jump, and before "Old Elizabeth" brings DeWitt to the future, there should be 2 Elizabeths in the same reality.
This brings up a number of questions:
- Why was Songbird looking for Elizabeth in the first place, when she's locked up safely?
- Why is Comstock telling the party that "you team up with the false prophet", when that didn't happened?