John Wayne, aged 57, was 36 years older than Michael Anderson Jr., who played his younger brother Bud.
Tommy Kirk was fired from the film after being arrested for possession of marijuana at a party on Christmas Eve 1964. Photographs of him wearing police handcuffs made the front pages of newspapers, and consequently he found it increasingly difficult to get film roles.
According to her tombstone, Katie Elder was 64 when she died. Her eldest son is played by 57-year-old John Wayne.
Despite this being a big-budget movie with a large cast, Karl Swenson was utilized to play two parts. He played "Doc Isdell" and also the bartender in the scene where the Dean Martin character auctioned his eye. The bartender part actually had more lines of dialogue.
Filming was due to begin in September 1964, but had to be delayed until January 1965 after John Wayne was diagnosed with lung cancer.
In western history, there is a famous Katie Elder: "Big Nose" Kate Elder, a prostitute and girlfriend of legendary gunfighter John "Doc" Holliday.
Remade in a modern setting as Four Brothers.
The hearse featured at the funeral of Katie Elder currently resides in front of the Haunted Mansion at Walt Disney World.
This film premiered on ABC television the same night as the infamous "Heidi" incident on NBC.
This picture marked the return of John Wayne to work after having a cancerous lung removed just four months earlier. He insisted on doing all his own stunts to show the public that the illness hadn't slowed him down.
When John Wayne is dragged into the river, you can hear a child calling out, "Dad!". This was his three-year-old son Ethan Wayne, who was watching off camera and knew how ill his father was.