Textureless Mario Anomaly

The Textureless Mario Anomaly is an anomaly only known to exist in individual personalized copies. Encountering this anomaly implies future bugs and crashes.

While this anomaly is active, the HUD and screen will flicker. Various 3D objects, the pause screen, and other map geometry will appear to be black. When the player interacts with the objects, the game will freeze or crash. In more personalized copies, an error screen will appear instead. Water textures will also appear to be completely invisible. When this happens, the music and sound effects will not play while the anomaly is present.

Documentation and appearances
Footage of this anomaly occurring can be found in a video made by SwankyBox on his channel SwankyZone SwankyBox has also made a video explaining how he discovered this anomaly. Watch his video here

Greenio's Tapes
This anomaly appears on one of Greenio's tapes, specifically in 11.15.95, where he briefly appears in 1:20 in the room with the trapdoor to Bowser in the Dark World. The screen goes black, and then this anomaly shows up close to the camera in the black background with the message "I'M NOT HAVING FUN," then his red and blue color turn black, and the screen goes black.

Further text in the video shows the entity to take on a more benevolent manner, advising and pleading with the viewer to find their way to the Fourth Floor and to end the source of the suffering of likely itself and others.

It also appears in the videos Beta Bob-Omb Battlefield, Deeper Cavern, Genesis and Aftermath.

Faceless
Super Mario 64 Machinimist MJacobBarker has made the Textureless Mario Anomaly appear in his 3-video series called "Faceless". Part 1 is here, Part 2 is here, and Part 3 is here. The series is a horror-drama Machinima. It focuses on Luigi running and trying to find ways to escape from Faceless Mario, Faceless Toad, Faceless Daisy, Faceless Peach, and even Faceless Luigi. The faced Mario, Toad, Peach, and Daisy are nowhere to be seen. Part 1 takes place in Big Boo's Haunt, Part 2 in Hazy Maze Cave, and Part 3 in Hazy Maze Cave and Peach's Castle. WARNING: The series does NOT have a happy ending.

StarCapCup64's Tapes
This anomaly appears during "TAPE 9/10" in the secret level "Aquarium Limbo". Mario appears as usual in the level, with no face detail with the level's HUD flashing continuously. Eventually Mario drowns, after hearing numerous screams inside the aquarium.

Theorizing
Considering that the only available footage of this anomaly was from a ROM hack where coins replace all the objects, Nintendo's adaptive A.I. is likely trying to reprimand and punish the player for tampering with the game. It could also be an anti-piracy system.

A hidden message within the footage of the anomaly seems to imply that the anomaly and Wet-Dry World are connected.