In a dream last night, I saw a photo of myself in a magazine doing something in a previous dream that I'd had several months ago. I immediately recognised the photo and the place at which it had been taken (not as having been a dream within the dream, but as part of my overall dream reality).
I have places, whole buildings that remain the same and that I often return to in my dreams. But this kind of dream reflection was a first, at least, that I can remember. So that was cool.