Princess Peach's Castle/Minor Anomalous Locations

The Minor Anomalous Locations of Princess Peach's Castle are a collection of areas that have been reported to be accessible in some personalized copies, but do not have their own floor or area similarly to a floor in most manifestations. The most common of these is an area behind the Mirror Room on the Second Floor, and an area Behind the Waterfall, though several other Minor Anomalous Locations have been documented.

Behind the Mirror
This area is the most common and well-known of all Minor Anomalous Locations. It is found behind the mirror in the Second Floor's Mirror Room. There are several reported ways to get past, such as Backwards Long Jumping, somehow breaking the mirror, or using a Vanish Cap to walk through the mirror. The area itself is usually minor, usually only holding a Castle's Secret Star or occasionally a secret level, most commonly accessed by jumping into the painting meant to represent Snowman's Land.

This area is notable for being accessible in Super Mario 64 DS. By using Luigi and the Power Flowers found in the Mirror Room, the player can pass through the mirror and reach this area. The only noteworthy aspects of this area is that the door in the room leads to a white void containing a Castle's Secret Star, as well as a painting of Wario that leads to Chief Chilly Challenge.

Behind the Waterfall
Main Article: Behind the Waterfall

This area is located behind the waterfall found in the Castle Grounds. It is most commonly accessed by using the Wing Cap found on the castle roof, using the 120-star cannon, or Backwards Long Jumping. This area was hypothesized due to Yoshi appearing to jump towards the waterfall after the player talks to them, and this has resulted in several theories about this area. This supposed area is also reportedly home of the Hammer Bros. anomaly.

Notably, the level Cavern of the Metal Cap appears to be the level that takes place behind the waterfall. Seen in the Level Select Screen, the level is referred to as "IN THE FALL", implying the waterfall in the Castle Grounds. The level also leads to the area around the waterfall when the player is pushed by the river in the level to the warp. In Super Mario 64 DS, the level is also referred to as Behind the Waterfall.

The Black Box
Were you looking for it's appearance in Super Mario 64 DS?

The Black Box is a hypothetical area seen in Super Mario 64 DS. Seen on the title screen's reflected castle in the lake, a strange black box on a tower can be seen. This oddity was theorized to actually be a secret level or area that would contain a special collectible, such as a new star or potentially Waluigi. However, this turned out to be untrue.

Notably, the Black Box has been reported to appear in some personalized copies of Super Mario 64, usually in the same location or somewhere else on the castle. It may usually be inaccessible, though some have reported accessing it using the Wing Cap, cannon, Backwards Long Jumping, or managing to jump into it from the castle roof. The contents of this area are inconsistent, though anomalous objects are usually reported in this area.

Behind the Portal
This area is a lesser reported Minor Anomalous Location found behind the Dire, Dire Docks portal in the Basement of Princess Peach's Castle. This area is reportedly where the Wario Apparition first spawns, though it does not appear to lead anywhere behind it. However, in some reports, the player has managed to make the portal disappear or glitch behind it to access a hidden area. This area can supposedly be the Castle Dungeon, or simply contain a Castle's Secret Star. However, some have reported this area leading to a unique level, or appearing as it's own distinct segment of the Basement. This location has been associated with the Big Bully's Key, which can reportedly be used to unlock this area.

Behind the Stained Glass Window
This Minor Anomalous Location is located behind the stained glass window seen on the outside of the castle. This area has usually been reported to be accessed by using the Wing Cap or cannon to fly into the stained glass, which will shatter and allow entrance. This has reportedly lead to the anomalous Delicious Cake level, which is notable due to Delicious Cake being theorized to be part of a scrapped introduction sequence though this area is usually only found at the end of the game. However, this area can also reportedly a large black area with Princess Peach inside, who will reportedly teleport the player to another level or give the player a Castle's Secret Star. This area is unique for being hypothesized to exist before it's first documentation. The stained glass window on the outside and on the inside have unique backgrounds, which implies there is a space between them. Princess Peach also appears in front of the stained glass window when rescued at the end of the game. Finally, some Toads claim that they and Princess Peach were trapped in the castle walls, and this could be interpreted as Bowser literally putting Princess Peach into this area in between the walls and stained glass windows.

Report 1
Recently Youtuber First Name Last Name has made 2 videos documenting Minor Anomalous Locations. The first one documents the Behind the Stained Glass Window area. It begins on the title screen before the player enters the Castle Grounds and uses the cannon to shoot into the stained glass window, which is noticeably now desaturated. Notably, the player only had 63 stars in this video, indicating that the Personalization A.I. removed the grill blocking the cannon. Upon colliding with the stained glass, they entered the Behind the Stained Glass Window area, taking the appearance of a large white brick hallway with red carpet, several stained glass windows similar to those seen in the room leading to the Princess' Secret Slide, and a regular version of the stained glass window behind them. The player walks down the hallway to a large room with the same large stained glass window seen in the foyer of the First Floor of Princess Peach's Castle, as well as a sign and Power Star. The player interacts with the sign, which reads:

"Sorry, Mario, but your princess is in another castle." Referencing the dialogue of Toads in the original Super Mario Bros.

The player looks around before grabbing the star, increasing their star count to 64, as the video ends. The next video documents Behind the Waterfall. The player, now playing as Luigi, goes on top of the castle and looks down to the waterfall as the footage cuts out and the player appears in the area, notably using the Rainbow Cap. The area appears as a large rectangular room with platforms leading to one star, another platform, and red coins on the floor of the level. It is believed something would have been on the floor to punish the player failing to complete the obstacle course. The player collects the red coins, spawning a star, and jumps on the platforms to a star, collects it, and the video ends.