- Retroactive Recognition:
- Season 5's "The Coffee House Set" has a pre-M*A*S*H Jamie Farr as a Beatnik named Itchy.
- Werner Klemperer appeared as Mike's professor in two season 3 episodes, while John Banner had a brief part in an episode from season 4. They'd go on to play Col. Klink and Sgt. Schultz, respectively.
- The mean girl Dodie faces at school in season 10's "Dodie's Dilemma" is Erin Moran, who'd play Joanie Cunningham on Happy Days.
- "Seinfeld" Is Unfunny: This was one of the first TV shows to acknowledge the passage of time without resorting to Status Quo Is God, allowing the three sons to grow older as their actors did. To get a better idea of how unprecedented this was, just check out the last couple seasons of Leave It to Beaver which insisted on having the now clearly adolescent Jerry Mathers still acting like a little kid.
YMMV / My Three Sons