Filming was hidden to public. The project wasn't announced until months after filming had wrapped.
The pie scene was done with just one take. Rooney Mara said it was vegan chocolate flavored and tasted terrible.
David Lowery, who both wrote and directed the film, characterized his idea to create a movie about a ghost as a primordial miasm in his brain, as he visioned a ghost exactly like the one that is presented in the movie. He believes that it is a very goofy image that is breaking from the norm in terms of how a story is told and the tools that are used for it.
The film reunites writer/director David Lowery with regular collaborator Casey Affleck, as well as Rooney Mara, both of whom starred in his feature Ain't Them Bodies Saints (2013).