Actor-Inspired Element: Goofing around during a break in the shoot, Ken Curtis did a routine where he told a story using an exaggerated version of the rural eastern Colorado accent (Curtis was born and raised in that area). John Ford liked it and told him to use that accent for his portrayal of Charlie McCorry.
The film made spectacular use of Utah's Monument Valley, playing the role of Texas. Semi-justifiable, since the scenic rock formations around Palo Duro Canyon in the Texas Panhandle were the stronghold of the Comanche, but still, there's nothing in that area even remotely close to the Monument Valley landscape.
Some exteriors were done in Colorado (the snow scenes), Alberta (the buffalo scene) as well as some in California (most notably Bronson Canyon, where the Ethan/Debbie climax takes place).
In Portugal, the film was released as A Desaparecida ("The Missing Girl").
In Brazil, it was Rastros de Ódio ("Tracks of Fear)".
In France, it was La Prisonnière du Désert ("Prisoner of the Desert"). This led to a strange "Blind Idiot" Translation moment in the English subtitles of Weekend, in which the translator apparently wasn't aware that The Searchers was being referenced in the dialogue and just had the characters talk about a movie called Prisoner of the Desert.
In Germany, it was Der Schwarze Falke ("The Black Falcon"), which also was the name of chief Scar in the dubbed version.
Dawson Casting: Jeffrey Hunter was nearly 29 at the time of filming, although Martin is supposed to be a teenager. There's a similar gap between 26-year-old Vera Miles and Laurie. Natalie Wood is a slighter example, since Debbie is 14 at the climax and Wood was 17.
Disowned Adaptation: Alan Le May actually did the disowning before he'd even finalized selling the rights to the novel. He'd moved to Hollywood in 1940, and had a rollercoaster career as a screenwriter, included a frustrating stint with Cecil B. Demille. Burned out with movies, Le May stipulated that he would never be asked to write the screenplay of the novel, and when he learned that another Auteur License holder, John Ford, was going to make the film, Le May decided it was best to just stay out of the way.
Fake Mixed Race: Jeffrey Hunter (born Henry McKinnies), solidly Irish-American, as Martin, who's 1/8th Cherokee.
Fake Nationality: German-born Henry Brandon as Comanche Chief Scar. All of the other Comanche are played by Navajo Indians.
Method Acting: According to Harry Carey Jr.'s book "Company of Heroes", John Wayne stayed in character between takes.
The actor playing Brad Jorgensen is the son of the actress who plays his mother. Pat Wayne appears in a scene with his father John Wayne. Ken Curtis (Charlie McCorry) was John Ford's son-in-law. Young Debbie is played by Lana Wood, Natalie's younger sister.
At the battle of the ford, where Captain Reverend Clayton accidentally fires off an unaimed shot after Ethan throws him a revolver. This accidentally happened to Ward Bond and John Ford decided to keep it in.
When Lieutenant Greenhill's report is being constantly interrupted by Ethan and Captain Clayton, that was Wayne and Ward Bond testing Pat Wayne's improvisational skills.
John Wayne was nursing a hangover when he shot the final scene, but since his slightly dazed appearance was perfect for Ethan in that last shot, John Ford didn't mind.
Also in the last scene, Wayne holding one arm with his other hand was a totally spontaneous gesture, replicating early cowboy star Harry Carey Sr. and his signature pose. Wayne had idolized Carey as a teen, John Ford had been Carey's mentor, and Carey's widow Olive (playing Mrs. Jorgensen) was on the other side of the door watching him, so it was a natural Shout-Out to make.
Troubled Production: Monument Valley was still quite remote at the time, without electricity or paved roads, and filming took place over the hot summer of 1955, with temperatures frequently soaring past 100 degrees Fahrenheit, so it wasn't a very comfortable shoot. John Ford wasn't happy with some of the shots done in Monument Valley, so he redid them when the company went back to Hollywood to film interiors, particularly the climax with Ethan and Debbie, shot in Bronson Canyon.
Fess Parker was John Ford's first choice for Martin, but he was under contract to Disney and Walt Disney apparently didn't even tell Parker about the offer. John Agar and Robert Wagner unsuccessfully lobbied for the part, which went to Wagner's close friend Jeffrey Hunter.
Before he wrote the novel, Alan Le May had written a screenplay treatment called African Pitfall that was essentially The Searchers in Africa, with a European settler child held captive by the Ndebele people. After hearing about the Cynthia Ann Parker story, he took some elements of his earlier story and mixed them with her story.