Carl Reiner appears again as Alan. He continues to hide his face; however, his profile can be seen briefly a couple of times.
Adamo sighting: Waiter in a restaurant.
I've noted more than once that the claim that Reiner didn't use contemporary references in the show is greatly exaggerated. This continues to be demonstrated frequently -- as in this episode, when Rob alludes to news magazine cover photos of Nikita Krushchev and Fidel Castro.