Was included as part of Food (1990), originally planned to be aired in the USA around August or September 1989 as the 12th episode of the 'The Jim Henson Hour', but that series was cancelled in August after only 9 episodes. So this episode of 'The Storyteller' was first shown in the USA in 1997 when HBO ran all 13 episodes of 'The Storyteller' (the 9 originals plus the 4 'Greek Myths') in December 1997 to January 1998.
Director Paul Weiland had previously worked with Jim Henson's Creature shop on a JVC commercial that featured an animatronic baby.
The Rule of Three - After the Princess' three brothers are transformed into ravens, she has to keep silent for three years, three months, three weeks, and three days to break the curse. She also gives birth to three sons after marrying the Prince, and speaks three minutes before noon (calling out three times) on the appointed day.
The story is based on the early German folk tale "The Six Swans", collected by the Brothers Grimm, and on other variants of the same tale type in the Aarne-Thompson-Uther catalog of folklore: #451 "The Brothers Who Were Turned into Birds".