If you look really closely at the Devan Shell sprite, you will see that it appears to be missing a frame around when he lands from a jump. Under normal circumstances, you can barely notice it, and if you paused the game to take a look, you would see nothing.

I'm not sure if this is a bug or an easter egg, but for some reason a totally unrelated frame is spliced into that spot. In some tilesets (they seem to be ones with modified palletes), instead of getting a blank frame, you get this message.



This image is not edited. That message is not part of the tileset.