I just thought of something... it's a long shot but....did they or did they not establish in earlier seasons that ghosts could not be captured on camera/filmed?
If that is the case, then what if the twist is that Evan/Rory faked his death as part of the producer's plan to increase the drama/tension in the house and he ends up being the one who survives because he got the fuck out of there before the blood moon really hit?
So basically.... the nurses = fake, pig man in bathroom = fake, Mason = fake, guy killed by chainsaw = real (unseen force), female producer who was killed = staged.
I could imagine a scenario where the producer has hired other actors to stir things up and they are able to move about the house without being discovered via hidden passages. We already know from earlier in the season the house has at least 1 of them.
Plus, the text in the episode said they all died under "mysterious" circumstances. If the ghosts were able to be filmed then it would not be mysterious at all. But an unseen force killing people? That fits the bill.
Things might get really interesting...