Paper Mario: The Thousand-Year Door

Paper Mario: The Thousand-Year Door, released in Japan as Paper Mario RPG, is a console role-playing game developed by Intelligent Systems and published by Nintendo for the Nintendo GameCube. The Thousand-Year Door is the fourth game in the Mario RPG series and the second in the Paper Mario series.

Professor Frankly's Gate
The gate outside Professor Frankly's house turns into a cyan block, and then disappears when he is opening it to show you the Thousand-Year Door.

Punies
The Punies may display incorrectly on all backends. EFB to Texture displays garbage, while EFB to Ram shows the Punies but distorts them. It only happens when they are standing still, and seems to happen more when they are facing left and not right. See. There is a workaround is using a custom texture to replace the garbage...

Cache Display Lists
Enabling Cache Display Lists causes bounding box glitches.

Koops the Koopa
He may only function in the center of the rooms. Makes certain puzzles impossible. Solution not found.