The screenplay was developed at the Sundance Screenwriters' Lab in Utah.
The team sport discussed and then played in the early part of the film is Hurling. Hurling (Irish: Iománaíocht/Iomáint), one of Ireland's native Gaelic games. Hurling is an outdoor team game of ancient Gaelic origin, administered in Ireland by the Gaelic Athletic Association. The game has ancient origins, and is known to have been played for over 3,000 years. In some ways similar to the North American game of Lacrosse, in terms of game play, both are often touted as the world's fastest team field game.
Padraig O'Loinsigh, who portrays Father Sweeney, choose to use a pseudonym, Patrick Lynch for his on screen credit. This was done purposefully. O'Loinsigh usually uses the pseudonym of Padraig (Patrick) Casey, but he chose Lynch instead, which is the same surname as the actor who portrays his life partner in the film, John Lynch, who portrays Father Matthew Francis.