Interesting, Jen. Surely Branagah knew of Yeats' insightful comment when using that visual. I'll have to check it out.
Interesting that Branagh's film used that hall of mirrors for such critical scenes as the "To be, or not to be" soliloquy!
I can see what he means by that idea. When you look into a mirror in a funhouse, you can see all kinds of things behind you, around you, and usually they're out of focus or difficult to really see and understand. Oftentimes, depending on the funhouse, you might be seeing yourself hundreds of times, but in a variety of shapes and sizes.
For me, I think the analogy is especially relevant to the character of Hamlet himself. With the exception of Horatio, there isn't a single person at Elsinore that he can trust, and everytime he turns around, there's someone else popping up, checking on him, spying on him, wondering what he's up to. In addition, there are his own feelings about himself and what he's supposed to be doing. He sees himself as hesitating too much and chastises himself for that, only to decide not to kill Claudius when he has the chance because he doesn't want to send the man to heaven during his prayers.
Anyway, that's what came to mind when I thought of mirrors and funhouses! :)