I don’t see what is “special” about mirrors. Many people seem to use them as a teleportation device, or as a reality check, or a remote window, or other things that involve the mirror being a portal or otherwise not solid.
I ask this because there are a lot of mirrors mentioned here, and I rarely see mirrors in any dreams of mine. In fact, I don’t think I’ve ever seen my reflection in a dream.
So, why do you pick mirrors for the things you do with them?
If I teleport, I usually do it without any props, or occasionally by tearing a hole in space.