Kurt Russell and Tim Matheson costarred the following season (after The Quest was cancelled) in the "Deadly Doubles" episode of Hawaii Five-O.
On, "The Longest Drive", part one, episode 8, broadcast 12/1/76, Two Persons and Mr. Hatcher have a conversation about having met before when Two Persons was a 10-year-old child with red hair and freckles. Kurt Russell and Dan O'Herlihy did work together about that time on The Travels of Jamie McPheeters, with Russell in the title role and O'Herlihy playing his father.