I believe that a Casting Gag is when the part an actor is playing is parodying a past part or scandal, while Actor Allusion is them playing a character that's very different but still having a joke about a role they did?
Actor Allusion is when there is a brief reference to a past role. Casting Gag is when a role is cast with a particular gag in mind.
Thus, in the Spin City example Christopher Lloyd showing up is a Casting Gag for Lloyd, but an Actor Allusion for Michael J. Fox.
Edited by EmeraldSource on Sep 1st 2024 at 10:05:11 AM
Comics are just words and pictures. You can do anything with words and pictures.Check out the TRS crowner
that improved the contrast between both tropes.
This was brought up before on the duplicate tropes discussion thread
. There wasn't much discussion at the time, though there was a comment that cleanup from past TRS may have been incomplete.

What is the difference between Actor Allusion and Casting Gag? I always get these two tropes confused, especially because both tropes involve refrences to an actor’s previous role(s).
♫ we’re so miserable and stunning ♫ - fall out boy