This episode marks the very first time we ever see the unobstructed face of Alan Brady (played by Carl Reiner). Previously he was featured voice only, seen only from behind, dressed like Santa (beard and all) in a Christmas episode, and seen on a magazine cover in full clown makeup.
Alan Brady's middle name is mentioned. It's "Lester".
We learn in this episode that Mel Cooley attended Princeton.
Contrary to the title, the story deals with fourteen letters rather than three.