Question about obvious plot point (to me) SPOILERS
Since the dad, Clyde? Had figured out that Emily was possessed by something that came out of the box, why didn't it ever occur to him to go back to the house where he bought the dang thing and ask if they knew anything? Then maybe he might have found out it's history sooner. Maybe he couldn't remember where the house was, but I would think they should have at least brought this up. I would think yard sale guy's mom would have something to say about the box, assuming she survived the attack.
Tis didn't make sense to me.
To each their own...opinion