Patrick McGoohan deserves a place on the Mount Rushmore of Columbo guest stars. Well, "guest star" doesn't quite do justice to his contributions to the beloved detective series. McGoohan appeared in four episodes, including his final on-screen television role, 1998's "Ashes to Ashes." The English-raised actor also directed five Columbo episodes, wrote the teleplay for another, and produced a couple, too.

Overall, the television icon, best known for his starring roles in Secret Agent (a.k.a. Danger Man) and The Prisoner, worked on Columbo from 1974 to 2000. Here, we're going to focus on "Identity Crisis," his first outing as a Columbo director. Because this episode is riddled with easter eggs for The Prisoner.

Peter Falk had his catchphrase — "Just one more thing…" — and McGoohan likewise had his own on The Prisoner. His character, the enigmatic Number Six, often says "Be seeing you." It must have delighted fans of the fantastic Sixties sci-fi series, then, to hear McGoohan tossing the line out again in "Identity Crisis." He bids farewell in an early scene with the line:

The following scene has another clever nod to Number Six, albeit a more sartorial one. McGoohan and Leslie Nielsen, playing two CIA operatives, walk through an amusement park. McGoohan sports a dark jacket with white trim — a cheeky fashion reference to the sportscoat worn by Number Six, as you can see at the top of this post.

There's more — as other fans have noted, McGoohan's character essentially becomes "number two" in his agency, a parallel to Number Two on The Prisoner.

There could be more for eagle-eyed viewers and classic television lovers to find!