In order to achieve the shape for the ghost Casey Affleck had to wear several petticoats and a hoop under the sheet.
Director David Lowery intended to use music from singer-songwriter Kesha in the background of the party scene. When producers reached out to Ke$ha, she not only allowed them to use her songs, she also arrived on set and served as an extra in the aforementioned scene.
Guillermo del Toro named this film his favorite of 2017, and cited it as a "masterpiece" and "one of best cinematic ghost stories ever made."
The pie scene was done with just one take. Rooney Mara said it was vegan chocolate flavored and tasted terrible.
The prognosticator has the longest piece of dialogue in the entire film. The monologue is more than double the combined dialogue of the main characters, who spend much of the film in silence.