Basil Rathbone, being a well known fencer in his own right, was asked how well Tyrone Power did in their scenes in which stunt doubles were not used. Rathbone responded, " Tyrone Power could fence Errol Flynn into a box!"
During filming, Tyrone Power was in the habit of taking an early morning swim in a pool that he insisted on being carefully pre-heated. Darryl F. Zanuck played a prank on him by arranging for the heating to be turned off. Power dived in and got such a shock that he later claimed he nearly had a heart attack. He got his revenge. Zanuck watched the dailies every day with a critical eye and one evening saw something unexpected; the cast and crew collaborated to film a spoof version of the hold-up scene where Zorro robs a coach carrying the Governor and his wife. When Zorro is supposed to slash his Z into the vehicle's upholstery, the camera reveals he has slashed "DZ". "Oh my God, it's Zanuck" his victims gasp. Power responds: "That's right, you bastards..." and describes the producer in very unflattering language.
In DC comic lore, this version of Zorro with Tyrone Power is the movie that a young Bruce Wayne goes to see the night his parents are mugged and shot by Joe Chill. After coming out of the movie and walking through an alley with Bruce is when they are mugged, and what leads to Batman's creation. This fact is mentioned in the 1986 Frank Miller comic The Dark Knight Returns.
Like most of the actors who portrayed Zorro at around this time, Tyrone Power was not of Hispanic heritage (he was of British descent).
The original working title for this film was "The Californian".