Director Mike Flanagan had repeatedly objected to the film being marketed as a "horror movie," and instead referred to it as a "fable" or a "supernatural drama."
None of the butterflies that appear early in the film have antennae. After a classmate draws antennae on Cody's picture of a butterfly, however, all of the butterflies and moths in the film have antennae, a small detail that shows how Cody's dreams are not only childlike, but easily influenced by others.
This movie was slated for wide release on September 25, 2016 until Relativity Media (the film's domestic distributor) filed for bankruptcy, leaving the fate of the film unknown. The film was later acquired by Netflix.
This movie was originally titled "Somnia," which would have made it the third film by Mike Flanagan featuring a single Latin word for a title after, Absentia (2011) and The Mirror (2013).
One of three movies directed by Mike Flanagan to be released in 2016, the others being Pas un bruit (2016) and Ouija : Les Origines (2016).