The book ("Midnight Mass") that Jessie throws at the dog in this movie was written by Kate Siegel's character from Still (2016) which was also directed by Mike Flanagan. It has subsequently been made into a Netflix Mini Series written and directed by Flanagan.
Features virtually no soundtrack during the course of the film.
When Gerald says, "All things serve the beam," this is a reference to author Stephen King's "Dark Tower" novel series.
The headboard of the bed is the lower half of the Lasser Glass from Oculus: Das Böse ist in dir (2013).