Mickey Mouse, both name and picture are owned by Disney so I doubt you could get a picture wthout copyright issues. If you just want to wear the shirt without using the name in your performance then you should be okay if you buy them off the shelves. Technically anything to do with a song is protected by copyright although a lot of small bands use themw ithout permission. You can also buy the right to use from various sites although the cost can vary. If you are planning on copying the Fantasmic show from Disney then everything you do technically is protected by copyright.