Although it is never mentioned in the film, Lady Alice More was not Margaret More's mother. Before Alice Sir Thomas More was married to a woman named Jane Colt with whom he had four children. More remarried almost immediately with Alice, who was a widow herself. They did not have any children, but she raised Margaret as her own.
Filmed over a period of 12 weeks.
Richard Harris was considered for the part of the king.
Five of the historical persons depicted in the film all had the first name Thomas: Sir Thomas More, Thomas Cardinal Wolsey, Thomas Cromwell, Archbishop Thomas Cranmer, and Thomas Howard (the Duke of Norfolk). Perhaps to avoid confusion, in the play and film, the only character referred to as Thomas is Thomas More.
The role of Cardinal Wolsey was played by John Gielgud in the early scenes and by Orson Welles later. Gielgud does not appear in the credits here but the role does appear on Gielgud's pages.