Nathan Fillion insisted that Guy Gardner sport the same bowl cut he does in the comics despite early discussions about changing the hairstyle. He said, "There was some talk about different hairstyles. There was some talk about some different types of things we were going to go. I was team bowl cut the whole way. It's canon. It's set. I said, If we don't do a bowl cut, we're going to hear about it."
Upon the release of the film, David Corenswet revealed that his predecessor, Henry Cavill, wrote him a letter of support and encouragement. Corenswet said he'd keep the details to himself, as it was a meaningful and personal gesture between him and Cavill.
Five Green Lantern rings were made for the film. Nathan Fillion kept one, and wore it to the premiere.
The return of Superman's iconic trunks was requested by David Corenswet, who justified it thusly: "I'm an alien from outer space who can fly and lift buildings, and I shoot laser beams out of my eyes that can dissolve things. I want kids to not be afraid of me. So, what am I going to wear?"
The Hall of Justice exterior was shot at the Cincinnati Union Terminal, which was used as the model for the Hall of Justice in O Desafio dos Super Amigos (1973). One of the interior Hall of Justice scenes shows a sign that says "To Trains" to further pay homage to the building's original function.
Will Reeve: The youngest child of former Superman Christopher Reeve appears as a reporter. In real life, Will is a television correspondent for ABC News. His cameo was first reported in July 2024 by Cleveland's local newspaper, The Plain Dealer. It was shot while exterior filming was underway in Cleveland's Public Square. Will was only three years old when his father was injured in the accident that left him paralyzed.