I was watching an episode of Leverage (The Ten L’il Grifters Job if any one cares).
They were working at a murder mystery, where everyone was supposed to come as a famous detective. Lot’s of Victorian style costumes.
The team was whining about their costumes as supplied by the con-woman (who was Irene Adler) - she’d made the thief Nancy Drew, the black computer hacker a Hardy Boy(!), and the hitter some cowboy era guy (looked vaguely Pinkerton-ish. The head guy (played by Timothy Hutton), comes in dressed in fairly modern clothes - hat, sport coat, no tie, sweater.
Con woman begins to berate him - “you promised to take this seriously, why aren’t you in costume”.
Hutton replies - “I’m the world’s greatest detective - Ellery Queen”. I remember watching that show in high school with my parents (with, of course, Jim Hutton (his dad) as Queen).
Castle is full of small tributes to previous shows the stars have been in. In one Halloween episode Ryan dressed as a doctor and Esposito dressed as a soldier. The respective actors had appeared on General Hospital and Generation Kill. And of course, Castle dressed like this.
Boston Legal had Shatner do a bunch of blink-and-you-miss-it callbacks to his Captain Kirk days (including his flip-phone’s signature tone) but gets bonus points for his speech to Tom Selleck, when he’s explaining that this place ain’t big enough for the both of 'em because it’s like they both used to be the leading man of a television series…
Happens all the time. I was watching the first season of Burke’s Law and in one episode Sammy Davis, Jr.* took out a cane and showed it to Burke, asking if it was his. In another, Burke reacts to a fake tombstone saying the dead person was killed by Bat Masterson. Of course, Gene Barry, who played Burke, also played Masterson, who carried a cane.
*Playing a character named Cordwainer Bird, and, yes, Harlan Ellison did write the episode.
How I Met Your Mother once did a Doogie Howser-type diary ending, with Neil Patrick Harris’ voice-over about what he learned today. (NPH used to play Doogie Howser as a kid.)
On “Bleep My Dad Says,” one episode took place in a karaoke bar and Ed (William Shatner) refused to sing “Rocket Man.” Of course, Shatner had famously (or infamously) performed “Rocket Man” at the 1978 Saturn Awards.