The Woman on the Beach - S2-E3
Plot hole: The episode has a small bit of supernatural hints, but the foundation of it is rooted in reality and acted by a living and not magical person. With that in mind, confirmed moments when the 'ghost' is Lisa in the flesh make no sense at all; her disappearance at the beginning is a Batman-like feat she shouldn't be able to execute. Not to mention that she is at the right place and time when Magnum visits the old abandoned estate; unless she just camps there 24/7, she had no way to know when Magnum (who visits 2 days after, not even right after the fact) would investigate.