In all recovered early builds of the game, the Fatten effect was provided by a funhouse mirror hidden in the large red maze (colloquially known as Hell). In Version 0.10, the mirror is removed and the effect is instead obtained by interacting with a tall, flashing humanoid (colloquially known as Strober) in the Docks B, and the portion of Hell where the mirror was once located is now empty. Incidentally, the Docks B is only accessible through Hell, preserving the association between the latter area and the effect.

Despite the mirror being removed from the normal course of play in the final build, it is still present in a debug room hidden in the game's code, functioning as it did in earlier versions. However, in the official English release, the text that appears when interacting with it, "★ふとる★", is corrupted due to it not being translated.