The Mirror is an item that is found in Alice is Dead and mentioned in The Rabbit's journal during Alice is Dead 3. It seemed to originally belong to Alice when she arrived from The Above. After Alice did not come back from a mission, The Rabbit noticed she had forgotten her mirror, which found its way inside his briefcase.
In Wonderland Forest, the Rabbit finds his briefcase inside a tree, and once he unlocks the briefcase, he finds the mirror and looks inside it, remembering who he is.
- This might be the eponymous looking glass from the sequel to Alice in Wonderland. According to his journal, the Rabbit saw some vivid and disturbing visions, possibly of the Above or an equally distorted looking glass world, after finding it.