The left hand and the right hand are 'mirror images' (of each other). = The left hand is the/a 'mirror image' of the right hand.
He's the 'mirror image' [=(more commonly) 'spitting image'] of his father. [=he looks just like his father]
She saw her reflection in the 'mirror'. = She looked at herself in the 'mirror'.
(..) Okay, I see it now. The big shiny one, right there. That one there? - That's the moon. - Oh, okay. . . Mirror, mirror, show her to me. Show me the princess. - Hmph. - Ah. Perfect. - (..)2001 Shrek
(..) My lord! We found it. Then what are you waiting for? Bring it in. - - Oh! - Magic mirror-- - Don't tell him anything! No! - - Evening. Mirror, mirror, on the wall. (..)2001 Shrek