Audrey Hepburn was originally offered the role of Joan. It was rumored that she turned it down because her husband, Mel Ferrer, wasn't approached for the part of the Dauphin, but Ferrer denied this.
Screenwriter Graham Greene added some lines to the original Shaw play when he adapted it for this movie, such as Warwick's "She'll burn, before the Pope gets to hear of it!"
A special effects accident caused Jean Seberg to catch fire during the pivotal scene where Joan is burned at the stake. Seberg sustained only minor injuries. On screen is the very disturbing moment when her neck catches fire, and Joan looks understandably shaken, but she does not scream or cry out during the burning.
Neophyte Jean Seberg was selected by Otto Preminger from a host of unknowns to make her screen debut in the title role. Though she received lukewarm notices, Seberg would survive for fifteen years in Hollywood. Her tragic end would conform to a pattern that haunted other leading ladies discovered by Preminger, including Maggie McNamara, and Dorothy Dandridge, all of whom either committed suicide or died young.
During pre-production, Otto Preminger had considered using English actors for English characters, and Irish actors for the French.