None of the actors involved in the film were paid any sort of fee for appearing.
No 46 is the house number of the Executive Producer.
No 46 was originally titled The Kindred after the book it was based on.
The hospital filmed in at the beginning is actually a place investigated by paranormal investigators.
Behind Elise when she creeps out of her bedroom to check on a strange noise, you can see a dark figure sitting on the bed. All the crew were accounted for and not one knows who or what the figure is.