Spencer Tracy was only able to narrate the film rather than play a part due to his health problems.
Debbie Reynolds and George Peppard are the only cast members who appear in three of the five sequences in the film. According to Ms. Reynolds, in an interview for the documentary Cinerama Adventure, her character of Lilith was originally supposed to have drowned in the river. However, it was decided that Lilith would best tie the generations of Prescotts together, so, she remained in the story to become an elderly lady in the film's conclusion.
John Ford complained that the sheer breadth of the Cinerama cameras meant that he had to dress his sets to a much wider degree than usual.
John Ford's habit was to always sit beside the camera while it was filming so he could watch the action intently. Unfortunately because of the triple lens on the Cinerama camera, he kept appearing in shot until director of photography Joseph LaShelle hit on the idea of building a rig that allowed Ford to sit above the camera.
Henry Hathaway was famous for his salty language. Debbie Reynolds instigated a swear jar on the set in an effort to curb him of his excesses - every time he swore, she would have to put some coins into the jar. Reynolds ended up losing quite a bit of money.
John Wayne had intended to play a character in the part directed by Henry Hathaway, but John Ford insisted he appear in the Civil War sequence.
John Wayne shot the key cameo of Gen.Sherman in five days.
Hope Lange was cast as a love interest for George Peppard's character, but her scenes were cut from the final print of the film. She portrayed young Julie Stuart, the daughter of Henry Fonda's character, Jethro Stuart. After Lang's scenes were deleted from the film, Julie was later portrayed by Carolyn Jones.
Gary Cooper had been offered the role of Linus Rawlings, but died before filming began. James Stewart then accepted the part despite feeling miscast.
James Stewart offered to play his own dead body in the Civil War story but was refused by John Ford who instead used a double who bore no resemblance to Stewart. When George Peppard imitates Stewart's voice during the grizzly bear reminiscence story he was reprimanded by Ford but yelled back that he wanted the audience to remember that Stewart played his father.
Russ Tamblyn and Bryan Russell also appear on the other 1962 Cinerama film The Wonderful World of the Brothers Grimm.
Raymond Massey made a career out of portraying Abraham Lincoln, having played him on stage, on TV ("The Day Lincoln Was Shot") and on film (Abe Lincoln in Illinois). This film marks the final time he played the President.
A comic book version of this film was published in conjunction with the film's release, as was the practice back then with all family and children's films. In the comic book, when Sheriff Ramsay (Lee J. Cobb) tries to prevent Zeb Rawlings (George Peppard) from going after the outlaw Gant (Eli Wallach), Rawlings whacks Ramsay over the head with his rifle and knocks him unconscious, which explains the bandage on Ramsay's forehead in the next scene. No such explanation is offered in the film; it is as if somebody had edited something out.
A lot of the actors were very intimidated by the 3 lens Cinerama camera and felt they had to elevate their performance to something approaching the way one performs on the theatrical stage as opposed to the more subtle style of acting normally required in front of a camera. This is why a lot of the actors in the film come across as being quite over-the-top.
All four cinematographers were Oscar-winners.
Although James Stewart's character was only supposed to be 28 in the movie, Stewart was actually nearly 54 at the time of filming.
Among the stars who were approached to take part in the film but did not were Marlon Brando, Kirk Douglas, Doris Day, Cary Grant, Audrey Hepburn, James Cagney, Bing Crosby, Frank Sinatra, Burt Lancaster, Shirley MacLaine and Kim Novak.
An intermission was required to allow the projectionists enough time to re-thread the three projectors and synchronize the sound.