This video shows you how to unlock all of the mickey mouse outfits from the Castle of Illusion Starring Mickey Mouse HD. These are nice Costumes.
List of unlockable costumes you can get from the game.
Classic Outfit
How to unlock: Default.
Explorer Outfit
How to unlock: Collect 5 Donald's Chili Peppers.
Magician Outfit:
How to unlock: Collect 5 Playing Cards.
Knight Outfit:
How to unlock: Rescue Minnie (Translation: Beat the game).
The point of the costumes are just for cosmetic use & the purpose of using them is so you can replay the game for time trials and missing diamonds/collectibles.
If you actually do find the collectibles in a row; you're bound to use one of the outfits to finish the remaining of the game which lasts short. The Knight outfit however is meant for replaying since it gets unlocked at the end of the game.
There is a "Castle Statue Piece" that are also collectibles but are not required to unlock an outfit. As far as I know, the purpose of that is to unlock a Trophy/Achievement.
FEB 2014 NOTE: Don't mind the dislikes. For some weird reason, if you find full hours of Disney Cartoons, etc., they get tons of dislikes. Possibly because they mistook the video for something else. Considering this is Mickey Mouse, it got affected along with the cartoons. DuckTales isn't that much affected though. My videos are our original creations and I use a lot of my creative input when creating them. I make videos such as transformative & instructional video game guides, let's play, and walkthroughs which sometimes include my commentary. All gameplay is my own & is recorded and edited solely by me. Permission to upload each game was provided by the game publisher.