The holiday of "Festivus" was created in 1966 by Daniel O'Keefe, the father of Dan O'Keefe, one of the show's writers. He invented many of the traditions later included in the "Seinfeld" episode, including the airing of grievances.
The original plan for this episode was to have two women playing the part of Gwen. Suzanne Krull was to be the ugly Gwen while Karen Fineman would be the pretty Gwen. In the end it was decided having the same role played by two different women would be too confusing for the audience so Fineman played the part of both Gwens instead.
Tracy Letts, the Counter Guy, won the 2008 Pulitzer Prize for Drama for his play "August: Osage County." In an episode of "Comedians in Cars Getting Coffee," Seinfeld is stunned when Julia Louis-Dreyfus informs him that an actor who played a bit part on their show went on to win a Pulitzer.
This episode marks the first mention of Festivus.
Allen Salkin wrote the book, "Festivus: The Holiday for the Rest of Us," about the celebration of Festivus in the real world.