I instituted the tag “Watching yourself” for movies in which an actor (A) plays an actor (B) and B watches a film in which A actually appeared. So, for example, in Two Weeks in Another Town, Kirk Douglas plays washed-up Hollywood star Jack Andrus, who in one scene watches a clip, supposedly of one of his old movies, but really of Douglas in The Bad and the Beautiful. Click on “Watching yourself” in the Tag Cloud at bottom right if you want to see more examples.
I now realize “watching yourself” can apply to directors as well as writers. After all, Vincente Minelli directed both The Bad and the Beautiful and Two Weeks in Another Town, so the clip of the former in the latter could be considered a sort of Hitchcockian cameo. I’ve got another example, which I learned about via the sleuthing of Jeremy James Prutchick on YouTube. It’s a brief scene (don’t blink) from Steven Spielberg’s Jurassic Park (1993). The creator of the cloned-dinosaur park, John Hammond (Richard Attenborough), is admonishing lead programmer Dennis Nedry (Wayne Knight–Seinfeld‘s Newman).
Don’t feel bad if you missed it — but in the last image, on the left side of Dennis’s computer monitor, is a scene from Spielberg’s first big hit, Jaws (1975): the one where Quint and Brody, on a boat, see the killer shark for the first time.
At another point, there’s another, totally out-of-sequence Jaws moment on the monitor, showing Roy Scheider as Chief Martin Brody. Prutchick helpfully enlarges it:
Here’s Prutchick’s frame-by-frame breakdown of the scene, which also includes a second Jaws moment on the monitor.