Mirror Room

The Mirror Room is a room in the Second Floor of Princess Peach's Castle with a mirror in the middle of the room. It is unclear if the room was reconstructed on the other side or is simply being reflected. In the mirrored version of the Mirror Room is the Snowman's Land painting, where a regular wall is on the non-mirrored room. Jumping into where the painting is will take the player to Snowman's Land. In Super Mario 64 DS, there are 2 Power Flowers that can be used to pass through the mirror as Luigi. The player can then walk through a door to collect a Castle's Secret Star, or go into a Wario painting to access Chief Chilly Challenge. There is also a Luigi painting in the non-mirrored room that Luigi leaves when he is defeated in Chief Chilly Challenge.

The Forbidden Door
In the regular Super Mario 64, the door mirrored in the Mirror Room is inaccessible. Some have theorized there is something behind the door. Some say it's the same as Super Mario 64 DS, some say it's nothing, others say it's an entire Inverted Castle.

Behind The Mirror
Similarly to the Forbidden Door, Behind The Mirror is the name given to a rumor of being able to get behind the mirror in the Mirror Room.

Inside The Painting
Some people say that getting behind the mirror and into the Snowman's Land painting would lead to a new course.

Strange Reflections
Some people say that more than the Snowman's Land painting isn't seen in the regular part of the Mirror Room in their copies.