Katharine Hepburn bested Peter O'Toole as the top dog on the set. Known to be something of a tyrant on most of his shoots, O'Toole meekly obliged, when she told him, "Peter, stop towering over me. Come and sit down and try to look respectable." O'Toole readily admitted in her presence that she reduced him "to a shadow of my former gay-dog self. She is terrifying. It is sheer masochism working with her. She has been sent by some dark fate to nag and torment me." Her reply: "Don't be so silly. We are going to get on very well. You are Irish, and you make me laugh. In any case, I am on to you, and you to me."
As of 2023, Katharine Hepburn is the only person to win four Academy Awards for acting. She won Best Actress for Morning Glory (1933), Guess Who's Coming to Dinner (1967), this movie, and On Golden Pond (1981).
Katharine Hepburn was descended from Eleanor of Aquitaine through numerous family lines, from both Eleanor's marriages to Louis VII, King of France, and Henry II, King of England.
Director Anthony Harvey and art director Peter Murton decided to make the setting as true as possible to the times. Although the principal characters were royalty, they lived in drafty, dirty castles.
Katharine Hepburn occasionally berated Peter O'Toole and Anthony Hopkins for showing up on-set up drunk or hung-over.