Marx Brothers made a guest appearance to introduce the "Tonight Show's" new host, Johnny Carson. Around 1960, the acclaimed director Billy Wilder considered writing and directing a new Marx Brothers film. Tentatively titled "A Day at the U.N.", it was to be a comedy of international intrigue set around the United Nations building in New York. Wilder had discussions with Groucho and Gummo, but the project was put on hold because of Harpo's ill-health and abandoned when Chico died in 1961. He was 74. Three years later, on September 28, 1964, Harpo died at the age of 75 of a heart attack
Things Which Have Never Yet Been Done (Skyler Wexler) undergoes bone marrow extraction to donate to Cosima in an attempt to cure Cosima's illness. Alison and her husband Donnie (Kristian Bruun) attempt to bury Dr. Aldous Leekie's body, while Helena attempts to escape from the ranch of the Proletheans, a religious extremist group. "Things Which Have Never Yet Been Done" marked the first on-screen appearance of Kathryn Alexandre, who also works on the show as Maslany's "clone double" when filming scenes where multiple clones interact. The episode was filmed at various locations in Toronto and the title was taken from Francis Bacon's work "Novum Organum". It was