In February 2021, A24 announced the film, then titled Disappointment Blvd., with Joaquin Phoenix on board to star in the leading role. The film's ensemble cast was announced in June and July. Co-star Stephen McKinley Henderson described Aster and Phoenix as "so simpatico ... their way of working together was like they were really old friends. They could get upset and make up in the span of seconds, it seemed. But the work was always the better for it." During a Q&A session on April 1, 2023 with actress Emma Stone, Aster recounted an incident in which, during the shooting of a “very intense” scene involving Phoenix's co-star Patti LuPone, Phoenix suddenly collapsed and lost consciousness as a result of the physical intensity of his stunts, which included breaking through glass. Initially annoyed because "it was a really good take", Aster realized it was serious as "[Phoenix] was letting people touch him and people were tending to him and he was allowing it".
