Jim Henson's The Cube (1969) is about a guy who finds himself trapped inside a 4 x 4 cube. Other people come inside to visit, but he can't seem to leave with them, even if those characters invite him out. Snip from dialogue:
Professor: Excuse me, I know this is a bad time but I just wanted to congratulate you and shake your hand.[Ed note: Or, that it's a YouTube play.] Video Link, here's a better quality link, more about the short on IMDB. (Thanks, Zack Lara, and Randy Perry)
The Man in the Cube: Oh? On what?
Professor: Well, as I interpret what you're doing here, this is all a very complex discussion of Reality versus Illusion. The perfect subject for the television medium!
The Man in the Cube: What do you mean, television?
Professor: Well, this is a television play.
The Man in the Cube: What?
Professor: Oh, you don't believe that?
The Man in the Cube: Of course not!
Professor: I should have thought you'd want to. After all, there's only one other possible explanation.
The Man in the Cube: Which is?
Professor: Hallucination. That you are altogether insane.
Previously on BB:
Reader comment: Marc in Barcelona, Spain says:
Hey Xeni, I'm a boingboing.net maniac! Your blog is great. I wanted to add my 2 cents into that story about Jim Henson you just posted. There's a film from the famous Spanish surrealist-Director "Luis Buñuel" called "El Angel Exterminador".
I suspect Jim Henson took the idea from that film.
The plot summary from IMDB :"After a lavish dinner party, the guests find themselves mysteriously unable to leave the room... and over the next few days all the elaborate pretenses and facades that they've built up by virtue of their position in society collapse completely as they become reduced to living like animals... "I've watched it and it's an excellent movie. I strongly recommend it to you.