There's a classic conundrum between divine foreknowledge and libertarian freedom. Freewill theists think the future is open. The future doesn't exist. There are alternate future timelines. Which one becomes the actual future depends on the choices free agents make. Yet that generates well-known problems for the possibility of foreknowledge, or vice versa. For a recent treatment, cf. John Martin Fischer, Our Fate: Essays on God and Freewill (OUP 2016).
In that regard, it's interesting to flip this around by comparing precognition with retrocognition. Just as there's evidence for precognition, there's some evidence for retrocognition, although that's not as well documented. But we could discuss it in principle.
Obviously, it's often possible to naturally know about past events. Take my memory of events I personally witnessed or experienced. Likewise, there can be various kinds of evidence for past events. That's the stuff of history, archeology, and geology.
However, I'm referring to incidents from the past which an individual wouldn't naturally be in a position to know about. Suppose I could see the past. Have a dream or vision about a past event. Even if (ex hypothesi) the future is open, it is now too late for the past to be open. That's over and done with. That's what makes it past.
Would retrocognition be possible if the past was indeterminate? If there were multiple alternate outcomes, no one of which was the real past, in contrast to the others? Isn't that wildly counterintuitive?