Robert Bolt borrowed the title from Robert Whittinton, a contemporary of Thomas More, who in 1520 wrote of him: "More is a man of an angel's wit and singular learning; I know not his fellow. For where is the man of that gentleness, lowliness and affability? And, as time requireth, a man of marvelous mirth and pastimes, and sometime of as sad gravity: a man for all seasons."
According to Orson Welles, he had Fred Zinnemann removed from the set and directed his scenes himself. However, in his autobiography, Zinnemann - while discussing the casting of, and working with, Welles - makes no mention of this.
Charlton Heston lobbied heavily for the role of Thomas More, but was never seriously considered by the producers as a candidate for the role. Heston would go on to play More in several stage productions of the play and ultimately film a television production of it in 1988.
One of only 4 productions to win both the Best Play Tony (1962) and the Best Picture Oscar (1966). The other 3 are My Fair Lady (1964) (1957/1964), The Sound of Music (1965) (1960/1965) and Amadeus (1984) (1981/1984).
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.
Five of the historical persons depicted in the film all had the first name Thomas: Sir Thomas More, Cardinal Thomas Wolsey, Thomas Cromwell, Archbishop Thomas Cranmer, and Thomas Howard, Duke of Norfolk. Perhaps to avoid confusion, in the play and film, the only character referred to as Thomas is Thomas More.
In the first London run of the play, Leo McKern played not Cromwell but the Common Man, a narrator-figure who addresses the audience and plays several characters in the story - More's servant Matthew, the man who rows him home, his jailer, etc. These characters also appear in the film, but are played by several actors. The original stage device of having them all played by the same actor was kept in A Man for All Seasons (1988). In the play, the lines stating what happened to the historical figures after the play's end are spoken by the 'Common Man'; in the film, they are spoken in voice-over at the end by Colin Blakely, who plays Matthew.
Robert Shaw became the second actor to be nominated for an Oscar for playing Henry VIII after Charles Laughton. Later Richard Burton was nominated for playing him too, making it the only character to produce 3 separate nominations.
This was the only time Robert Shaw and Orson Welles worked together, but in 1970 when Shaw was renting Welles's Madrid home, he accidentally started a fire which destroyed many of Orson's unfinished scripts and films,.