Rosamund Pike revealed in an interview that she and Christian Bale barely spoke during filming outside of shooting their scenes, saying that Bale "would keep a distance. Our characters in 'Hostiles' are quite dysfunctional but have this profound connection that we let happen without ever really talking about it."

The film was shot in chronological order.

The widow of credited screenwriter Donald E. Stewart found the "Hostiles" script when moving houses. Stewart, who died in 1999, had not shipped the manuscript to any studios, and his wife was surprised to come across it. After seeing Crazy Heart (2009) and Out of the Furnace (2013), she felt that Scott Cooper was the right man to shepherd it towards the screen.

Christian Bale and Rosamund Pike were supposed to work together a year earlier, in a movie called The Deep Blue Good-By, which would have been directed by James Mangold, but the project fell through due to Bale's leg injuries. Bale recovered, but the project did not resurface and he teamed up with Pike for this film.

The film went into production without a distributor. With a budget of almost $40m, this was a huge gamble for financier Ken Kao.

Director Scott Cooper wrote the characters of Christian Bale, Wes Studi, Jesse Plemons, Rory Cochrane, Q'orianka Kilcher, Adam Beach, Stephen Lang and Bill Camp expressly for each actor to play.

Christian Bale and Ben Foster starred together in another western, 3:10 to Yuma (2007), a decade prior to this film.

The film takes place mostly outdoors. As the movie was shot on location in New Mexico and Arizona during monsoon season, the cast and crew were exposed to the elements. Indeed, filming had to be often shut down for a time because of lightning storms.

Director Scott Cooper became interested in casting Rosamund Pike after seeing her in the music video Massive Attack: Voodoo in My Blood (2016).

According to director Scott Cooper, Timothée Chalamet was the only actor who had to audition for the film.

The book Capt. Blocker is reading at the beginning of the movie is Julius Caesar's Commentarii De Bello Gallico (The Gallic War) in the original Latin. The page shown is from Book V, describing the social and economic structure of 1st century BCE ancient Kent. In 55 BCE Caesar invaded briefly the south of the England.

Q'orianka Kilcher said she suffered from heat stroke during filming.

Rory Cochrane and Jesse Plemons both starred in Black Mass (2015), which was also directed by Scott Cooper.

Christian Bale, Q'orianka Kilcher and Wes Studi also starred in The New World (2005).

Actors Wes Studi and Adam Beach have appeared together in other films, most notably as Detective Joe Leaphorn and Sargent Jim Chee in three movies based on books written by Tony Hillerman: A Thief of Time (2004), Coyote Waits (2003) and Skinwalkers (2006). They have also appeared in other films including Bury My Heart at Wounded Knee (2007).

Christian Bale, Stephen Lang and Rory Cochrane previously worked together in Public Enemies (2009).

This was the second time actor Christian Bale and director Scott Cooper worked together, after Out of the Furnace (2013).

This was the second Western film Christian Bale starred in.

This was the second collaboration between Scott Cooper and Jesse Plemons. The first was Black Mass (2015).

This was the second time Rosamond Pike worked with an actor who played Batman. She previously worked with Ben Affleck in Gone Girl (2014). Christian Bale played Batman in Christopher Nolan's The Dark Knight trilogy and Affleck played the character in the DC Extended Universe films.

This was the opening Red Carpet Gala movie for the 14th Dubai International Film Festival 2017.

This was the second film to co-star Wes Studi and Stephen Lang. The first was Avatar (2009).

The film had its world premiere at the Telluride Film Festival on September 2, 2017, and had a limited release in the United States by Entertainment Studios.

Jesse Plemmons and Ben Foster previously starred together in The Program (2015), which was about the scandal surrounding cyclist Lance Armstrong's doping.

Christian Bale initially had reservations about the closing of film, feeling it was "a movie ending," and would debate director Scott Cooper on the matter. Bale felt that his character should just disappear into the crowd never to be seen again. Trusting Cooper's vision, he filmed the scene as written and came to appreciate the ending for its hopefulness but also for the questions it raised about the future.