Lee Marvin drank real alcohol throughout the production, even though director Joshua Logan fought him about it. In most movies, the actors and actresses drink tea for whiskey and water for vodka. Marvin would only work if he got real liquor.

Soon after Ben, Pardner, and Mad Jack open their secret "gold mine" underneath No Name City, a young farmer is recruited to help dig. To emphasize the need for secrecy, Mad Jack threatens to shove a stick of dynamite in the farmer's mouth if he blabs. The film is set in 1849 or 1850, before California becomes a state. Dynamite wasn't yet invented (it was patented by Alfred Nobel in 1867).

After the end credits and the Paramount logo, the screen goes black and a closing medley of the songs is heard for several minutes.

On its release to what were then called "neighborhood theatres" (i.e. theatres which showed films that had ended their first runs downtown), the film's running time was shortened by having three songs eliminated, "I Still See Elisa", "The First Thing You Know", and "Gold Fever". This left both Lee Marvin and Clint Eastwood with only one solo song each. The film was restored to its original length for its first television showing, and has remained that way ever since.

Edited into The Kid Stays in the Picture (2002)