Thinking about Arthur **SPOILERS**
During the final seance, Myra "sees" that the girl is still alive. How could she have known this?
Perhaps she really is psychic, and saw the girl, or was able to read her husband's mind. Or maybe she really was communicating with Arthur the whole time!
If so, this is one wild plot: the evil ghost of a stillborn baby influences his psychic mother and henpecked father to kidnap and murder a girl. His dad doesn't believe in him, and secretly saves the girl. Arthur betrays his parents by spilling the beans during a seance attended by suspicious police.
That would make Arthur one of the most extraordinary horror villains. He operates under the cover that he never existed, and only his seemingly delusional mother can sense him.
Any other thoughts on Arthur?