Anton Lesser is the focal character - Sir Thomas More - in this episode. His daughter, Lily Lesser also appears as Princess Mary.
Claire Foy (Anne Boleyn) & Kate Phillips (Jane Seymour) also worked together on The Crown (2016) as Queen Elizabeth II & Venetia Scott respectively.
Tom Holland (Gregory Cromwell) and Emma Hiddleston (Meg More) both make appearances in this episode. Emma's brother, Tom Hiddleston and Tom are both a part of the Marvel Cinematic Universe and have appeared in Avengers: Infinity War (2018). They played Loki and Peter Parker/Spider-Man respectively.