Unlock New Game+
In order to unlock this extra "New Game+" mode you have to beat the game once.
Unlock Song Listen
In order to unlock this "Song Listen" you have to beat the New Game+.
Go through couple dungeons then go down the stairs fourth cloud piece is there.
The secret room in the grasslands
Once you've found hot dog princess's knight, AND princess bubblegum's pantyhose, you can go into the secret room optional: jake's umbrella power.When you enter candy kingdom you cross a bridge. walk left then go on another bridge. Break the stoned with jake's help and go to four trees. There is a guy who copies your every move to get past him to the treasure (a level up boost) move back and forth back and forth but don't go over the edge jump over him and get the treasure! He'll fall off the cliff.
Hidden Secret Screen
In order to unlock this Secret Screen you have to press: Up(2x), Down(2x), Left, Right, Left, Right, B, lastly A when you are at the title screen.
In Lemongrab's castle, go into Billy's cell and use a pair of Beautious Wings to get the Enchiridion. You may have to move around a little, but it's there.