Pat Cunnane, son of Congresswoman Madeline Dean, wrote the script for Eternity, and it was voted onto The Black List of best unproduced screenplays in 2022.
In March 2024, David Freyne was hired to direct the film for A24 with Elizabeth Olsen, Miles Teller and Callum Turner signed in to star.
Principal photography began on May 24, 2024, in Vancouver, and production wrapped on July 5, 2024.