In an emulator, spawning a Goomba and moving it in the path of a jumping Cheep Cheep will normally cause the Cheep Cheep to hit and kill the Goomba, despite these two enemies never normally encountering each other in the game. However, in World 1-1, spawning a Giant Tail Goomba in front of the rivers at the start of the level to try and get the Cheep Cheep to kill it will instead cause the Tail Goomba to fly off-screen as it has a preset path it travels and attacks on instead of just following Mario/Luigi wherever he walks. Off-screen, it will perform its Tail Swing attack that will mysteriously cause the level itself to take damage, effectively "killing it" and forcing the level to erase almost its entire memory and be collected as one coin, including Mario/Luigi. The game then disables you from quitting or restarting the level.