The pie scene was done with just one take. Rooney Mara said it was vegan chocolate flavored and tasted terrible.
Filming was hidden to public. The project wasn't announced until months after filming had wrapped.
In order to achieve the shape for the ghost Casey Affleck had to wear several petticoats and a hoop under the sheet.
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.
Director David Lowery intended to use music from singer-songwriter Ke$ha in the background of the squatters party scene. When producers reached out to Kesha, she not only allowed them to use her songs, she also arrived on set and served as an extra in the aforementioned scene.
David Lowery wrote the film as a reaction to the 2015 New Yorker article The Really Big One by Kathryn Schulz. The article discusses potential natural disasters that could destroy humanity much in the same vein as the monologue given by the Prognosticator in the middle of the dance party who predicts that humanity as a whole is doomed.
Several variations of pies were baked and tested in preparation for the pie eating scene. Rooney Mara, a self-confessed picky eater, opted for a reduced sugar, gluten-free and vegan chocolate pie. Director David Lowery said it was delicious.
Rooney Mara had never eaten pie before filming the scene in which she eats an entire pie.
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).
In one scene the young Hispanic girl Yasmina plays on the piano a few bars of the Ode to Joy, from Beethoven's Ninth Symphony. In a later scene the Prognosticator speaks at length about this symphony, during which the film's musical score also begins to play part of this symphony.
In the Pie Scene, it takes Rooney Mara from the time she sits down and starts eating to when she can't eat no more and runs to the bathroom, exactly 4 Minutes!
The card trick shown at the party is called "Haunted Deck". To find the card, it uses a secret method that is often called a "loop".