Audrey Hepburn was originally offered the role of Joan. It was rumored that she turned it down because her husband, Mel Ferrer, wasn't offered the role of the Dauphin, but Ferrer denied this.
Screenwriter Graham Greene, a famous author, 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!"
During pre-production, Otto Preminger had considered using English actors for English characters, and Irish actors for the French.
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 Jill Haworth, Maggie McNamara, and Dorothy Dandridge, all of whom either committed suicide or died young.
A special effects accident caused Jean Seberg to catch on fire during the pivotal scene where Joan of Arc is burned at the stake. Seberg sustained only minor injuries. On screen is the very disturbing moment when her neck catches on fire, and Joan looks understandably shaken, but she does not scream or cry out during the burning.
Jean-Luc Godard's appreciation for this and Bonjour Tristesse (1958) led Jean Seberg to be cast as the lead in Breathless (1960).
Jean Seberg's performance as Joan was soundly panned, and Otto Preminger was heavily criticized for casting an inexperienced unknown in a role which required her to act with veteran actors such as John Gielgud, Anton Walbrook, Felix Aylmer, and others. In Seberg and Preminger's defense, she was the exact same age as the teenage Joan was at her martyrdom; Ingrid Bergman was 33 and Maria Falconetti 36 when they played her.