I don't think you're supposed to think about that too deeply, because if you did, then you'd find a huge problem with the basic premise itself. Human memory is nothing like it's depicted in the ep - it's not a hi-res video recording that can be played back. Memories are extremely meliable and prone to editing/revision. This is why you aren't supposed to ask leading questions in courts or in scientific research. Memories are far too unreliable to be of much if any use as depicted. At best, you might use them to as leads in a conventional, evidence-based investigation.