To unlock Mirror Mode in Mario Kart World, you want to complete the following list of tasks: Once you have completed the above checklist, go ahead and complete the Special Cup (Grand Prix) once more. After the Grand Prix, the credits will roll and then be followed by a brief cutscene. You will then get the ‘You have unlocked Mirror Mode’ pop-up!

Spotted by IGN, an account on X called Ninjinaut showcased the Mirror Mode Easter egg in Free Roam for Mario Kart World. The video sees Baby Rosalina jumping into the window, which is a direct callback to Super Mario 64's mechanic for accessing new worlds.