How would we determine that the experience happened during that time and not as a memory created when oxygen reached the brain after, or so on? If you assume th

How would we determine that the experience happened during that time and not as a memory created when oxygen reached the brain after, or so on? If you assume that narrative memory is a little bit hallucinated (which I think is pretty observable, try dissociating a little and you can experience it) then many options are on the table.