From disc one's main menu, select 'Kingdoms'. You will see a map that lists 9 kingdoms and asks you to 'Search for the Hidden 10th Kingdom'. The cursor will be on the 1st Kingdom when you first start, so use your remote to move the highlight left to the 3rd Kingdom and then up to the 4th Kingdom. Now, move right and the cursor will position itself on a small castle. Press 'Enter'. You have found the 'Hidden 10th Kingdom,' as you can see from the text screen that comes up. But there's more. Once you've read the message, you can click 'Up' one more time to highlight the Magic Mirror. Selecting it reveals a short clip showing two of the characters entering the 10th Kingdom. Not that big of a deal, but I think it's pretty cool.