In an answer to another question, I wrote "characters in the later movie watch or discuss the earlier movie".
Then it occurred to me, have characters in an earlier movie watched or discussed a later movie?
It would take an extraordinary set of circumstances for it to happen -- perhaps a movie was expected or hoped for to such a degree, it showed up in a produced script, perhaps just a very lucky guess. Even more difficult would be getting footage of movie that is still a ways off.
At some point, someone in a movie from the 80's or 90's must have hoped for a Star Wars prequel, right? Or that some old TV show like Mod Squad or The Man From UNCLE would be re-made for the big screen?
Clarification: I'm hoping for something organic or accidental, not a deliberate promo by the studio.
Two characters in a 90's movies who in-universe are Star Wars fans talking about how great it would be if George Lucas made some more Star Wars movies is Hilarious In Hindsight. Nick Fury in a stinger inviting the hero to join the next Marvel ensemble-flick is eye-rolling to everybody who isn't a fan-boy.
Further clarification: Seriously, no promos.