Groucho Marx had just published his sixth book, 'The Groucho Letters: Letters from and to Groucho Marx' (Simon & Schuster, 1967), containing a collection of his personal correspondence with literary figures such as Booth Tarkington, T.S. Eliot and Carl Sandburg.
According to production logs, there was not enough time for a contestant who "Designs and Makes Sunglasses" to appear. However, since this episode was prerecorded, the participant appeared in episode Candice Bergen (1967), which was broadcast live right after this previous taping. Unfortunately, no kinescope copy of that live show survived and its considered lost.