The Magic Mirror is a mirror that acts as a communications device, which, when activated, shows a secret contact played by Austin.
The Mirror is owned by Princess Uniqua and Princess Tasha. Although he is only referred to as "Magic Mirror", Austin clearly acts as a secret contact for the princesses, and most likely has his own station somewhere in the Tower Castle.
The Magic Mirror is mostly of a silver color. When shown in the mirror, Austin is wearing a blue outfit and a black headset.
Austin has only played as the magic mirror in one episode of The Backyardigans: Break Out!, from season four.