This is Emily Browning's fourth movie in which she acts as a mental patient. The previous ones were The Uninvited (2009), Sucker Punch (2011) and God Help the Girl (2014).
Ron Livingston sang "How Great Thou Art" as Elvis and Emily Browning sang "I Don't Want to Die"
The actor playing Karen's father, John Livingston is the brother of Ron Livingston, who plays Elvis.