Trivia: Christian Bale continued an impressive history of weight gain and loss for this part - he'd put on weight for his role in Vice, and had 7 months to drop it all to play Ken Miles. He's said he just didn't eat. He's previously lost weight for The Machinist, and then gained it all back in short order for Batman Begins.
Trivia: James Mangold wanted to make the film 10 years previously, but it was stuck in development hell. After the success of directing Logan, he was hired as director and reworked the script with other writers, managed to lower the budget, and the film was finally put into production.