The film is dedicated to David John Mackenzie (1929-2015) and Ursula Sybil Mackenzie (1940-2015), the parents of director David Mackenzie. Both died while he was making this film. You can also see references to them by their initials along with these years showing up on certain license plates throughout the film.
The phrase "come hell or high water" typically means "do whatever needs to be done, no matter the circumstances". It also refers to the "hell or high water clause" in a contract, usually a lease, which states that the payments must continue regardless of any difficulties the paying party may encounter. Both definitions apply to different parts of the plot in this movie.
Due to his tight schedule with Star Trek: Beyond (2016), Chris Pine was only available for two and a half weeks, and all his scenes had to be shot very rapidly and in sequence to maintain the required level of energy.
Toby offers his son a beer. Texas is one of ten states that allows underage minors to consume alcohol in specific locations, such as the privacy of home or in the presence of consenting and supervising family members.
Comancheria, the film's original title, is the region of New Mexico, West Texas, and nearby areas occupied by the Comanche before the 1860s.
Taylor Sheridan: The actor-turned-writer who wrote the film plays a cowboy whose cattle are chased by a grass fire.