A quick way to get a photoreal mirror with Superfly is to use the PhysicalSurface and set it up as per the image below:

                                                                                                                 

This is without going into the actual construction of a mirror that involves creating a glass layer, a reflective layer, and any additional imperfections you want to add to the surface(s).  I am currently working on another project but this is what the Superfly render looks like: