I have a reproduceable bug with the carousel. Particularly the bug occurs when creating a carousel with no items. Code to reproduce below:

Code:
var car = Ext.Viewport.add({xtype: carousel});
car.add({html: 'one'});
car.add({html: 'two'});
car.add({html: 'three'});
car.show();
Notice you cannot properly switch between carousel pages.