8 Glowing Rabbits

In the game, you may or may not have noticed, but after collecting at least 8 Power Stars and unlocking Mario, the various mini-game character color-coded rabbits around the castle (outside the castle grounds, courtyard, and inside) will randomly be glowing. If you catch eight of these glowing rabbits, then you'll be rewarded with a key that unlocks the white door in the room with the Mario, Luigi, and Wario character doors and the Princess's Secret Slide level. Open that door with any character, and after several seconds of hearing Boos' laughs, you'll instantly earn a secret Power Star.

How Do I Get All Of These Eight Glowing Rabbits?
They're so scarce, it's rare to find one. They won't appear unless you caught a regular rabbit. You can collect all the eight glowing rabbits with whichever character you choose, in any part of the castle, though we've expertly devised a formula that'll help get you all of the eight glowing bunnies the fastest. Change your character to Yoshi and step outside of the castle through the front door. At the end of the bridge there will always be three bunnies. The other three will be at the hedges on the left, the patch of flowers at the right, and in the drained moat. If you see one that's glowing, chase after it and catch it. There can also be multiple glowing ones at the same time. When you're done, go back into the castle through the same doors and then step right back out again. The six rabbits will all return to their places in front of the bridge, hedges, patch of flowers, and moat. If none are glowing, then just repeatedly enter and exit the castle and try again. This is by far the fastest way to summon all the eight glowing rabbits. Much like the rabbits, these rabbits are also remodeled after MIPS from the original Super Mario 64. The final glowing states that it is the "fastest" and "eldest". Additionally, they appear to be related to each other and are all male, as each rabbit then before states that it is the "second fastest of [their] eight brothers". If a glowing rabbit before the eighth one is caught, you get a chance to save your current progress.



Trivia

 * If you see the glowing rabbits, but don't catch them or catch them without saving your progress, you can still catch them later on.
 * Once all of the Glowing Rabbits are found, you cannot see them again. It's unknown where they go, but the regular rabbits will still remain.
 * The white door in the character selection room has no other purpose than to award one of the Castle Secret Stars. Before getting the star, and afterwards, all that happens when you enter the door, is hear Boos' laughs, and being forced to walk out again and groan.
 * You never see the room inside the white door either - the game camera stays outside, as it does for the three character doors.
 * The white door was originally going to be the key to Waluigi's door.