Denzel Washington and Chris Pratt were the first two actors cast. Antoine Fuqua knew that both men had expressed interest in appearing in a western. Getting Washington was easy, but Fuqua initially was unsure in which role Pratt would fit. On the second phone call between Fuqua and Pratt, the latter started to sing "Oh, Shenandoah", which Fuqua immediately declared that "Pratt is Steve McQueen".
According to director Antoine Fuqua, Martin Sensmeier was cast as Red Harvest because he auditioned with luxuriant, almost knee-length hair. Sensmeier wasn't told his hair was a selling point, and he cut his hair soon after. Fuqua was upset, then got the idea for Sensmeier to have his hair cut into a Mohawk.
Chris Pratt's character tells a story of a guy falling off a five-story building. At every floor the people hear him say, "So far, so good." This is an homage to Steve McQueen's character on the original The Magnificent Seven (1960) telling the same tale, except it was a ten-story building.
James Horner worked on this film after he and Antoine Fuqua became close friends while making Southpaw (2015). According to Fuqua, Horner's team visited him on the film's set in Baton Rouge, Louisiana, one month after Horner's accidental death, to deliver the completed score. Horner had been so inspired after reading the script that he composed the entire score during pre-production.
The characters use explosives produced by the Giant Powder Company of San Francisco. The company began operations in 1868, as the U.S.'s first manufacturer of dynamite, under exclusive license granted personally by Alfred Nobel, the inventor of dynamite.
The Gatling guns used in the film's time period were chambered in .45-70 Government, with a muzzle velocity of 1,600 feet per second, a 300-grain lead bullet, and a range of well over a mile. At the time, the Army's standard target was a 6 ft. x 6 ft. wooden target at 600 yards, well over the distance shown in this film. The .45-70 round was also used to shoot buffalo in the late 1800s. The range for the Gatling gun in the movie was more than accurate.
Although this film is not a straight remake of The Magnificent Seven (1960) and the characters have different names, parallels can be drawn between them. Chris and Sam are both team leaders and black-clothed guns for hire and leader of the team, as Sam. Vin and Faraday are both broke gambling drifters. Lee was a sharp shooter suffering from PTSD, similar to Robicheaux. Britt is a lethal knife fighter, as is Billy Rocks. Vasquez and Chico are both Mexican, though Chico was far less experienced. Bernado O'Reilly looks like a Native American, like Red Harvest. Harry is a large imposing man, much like Jack Horne.
Near the end, Ethan Hawke in the bell tower says to Billy Rocks, "Let me tell you something my daddy once said," pauses and continues, "well he said so many things." Bob Dylan said the same thing, almost verbatim, in his Grammy acceptance speech.
Antoine Fuqua met with studio executives to review actors for the film, but was unhappy that all of the actors under studio consideration were white. He felt the audience would be able to identify with characters who came from a wide variety of backgrounds, coming together for a common cause.
As a teenager, Antoine Fuqua was inspired to be a filmmaker after watching two films, The Magnificent Seven (1960) and Scarface (1983). He once said that he would lobby to do a remake of these films if there would be a plan to do so. Fortunately, he got his chance; producer Roger Birnbaum wanted to do a remake after leaving his position as co-chairman of MGM, saying the original film and its characters underline the theme of mortality, a theme that he holds after surviving a gastrointestinal tumor.
From the moment Faraday gets his horse and rides away, there are several musical beats from the original movie's theme song, but with different instruments, and only the first 9 familiar beats. The entire original theme song, sometimes called the Marlboro commercial song, is played during the end credits.
Sam Chisholm tells the Sheriff of Rose Creek to pass a message to Bartholomew Bogue: "Lincoln, like the President. Lincoln, Kansas". Lincoln, Kansas was founded in 1870, one year after Lincoln, New Mexico, where the Lincoln County War took place in 1878-1879. Several plot details mirror the range war, including a robber-baron exerting control over the town, the local sheriff being on the robber-baron's payroll, a group of gunfighters forming to fight the robber-baron (known as The Regulators in the Lincoln County War), the siege of the town (July 15-19 1878, known as the Battle of Lincoln), and a significant protagonist having the surname Chisholm (Cattle rancher John Chisholm in the Lincoln County War).
The trivia items below may give away important plot points.
The film takes place one year after the 1878 Lincoln County Land War, in which real-life antagonist Lawrence Murphy was also a corrupt business man like Bartholomew Bogue. One notable protagonist in the Lincoln County Land War was John Chisum, a business partner of Charles Goodnight.
When the Magnificent Seven are heading to the village with Emma Cullen and Teddy Q, they stop to camp for a night. Josh Faraday offers to teach Teddy Q some shooting lesson in exchange for a few drinks of Teddy's whiskey. He tells Teddy to try to take the King of Hearts from his hand. Faraday finally lets Teddy get the card, waits a few seconds, pulls out his gun, points it at Teddy, and says "it was never about the cards". It foreshadows the end of the movie. At the end of the movie, when Faraday rides towards the Gatling gun, he is shot and falls off his horse right next to the men and the gun. Unarmed, with a cigar in his mouth, he tries to light it, but struggles. The man in charge of the gun gives Faraday a light. A King of Hearts is in Faraday's pocket, hinting at Faraday's lesson to Teddy. Just like his lesson with Teddy Q, the men at the Gatling gun, for a brief moment, think they have won and let their guard down, only to find out that they have given Faraday what he needed to light the dynamite and destroy the gun. Just like his lesson, "it was never about the cards."
Although Steve McQueen's character survives the original 1960 movie, Chris Pratt's character (who is clearly based on McQueen's) dies similarly to Queen's character in Hell Is for Heroes (1962). McQueen charges a pillbox with a live satchel charge and sacrifices himself at the end of the film.