Platonism - A great packet trick!
Three cards are shown. Two are face down and one is face up. Let's say it is the Queen of Diamonds. Next one of the face down cards visibly reverses and rights itself up. Let's say it is the Queen of Hearts. Finally, the remaing card also visibly reverses and rights itself up. Let's say it is the Queen of Spades. You offer an explanation for these events.
You say that it is all done with mirrors. That being said, you now count out the three cards showing fronts and backs. The faces of the cards have changed to bright shinny mirrors! And the backs are now blank!
This is a great packet trick!