Press Minus to pause game play, then press Left, Right, Left, Right, Left, Right.
Music artist references
On the elves island, place the pointer over the animals. Some of them have names like Buni Jovi (Bon Jovi), Bruce Sproingsteen (Bruce Springsteen), Bunno (Bono), and Toad Nugent (Ted Nugent).
Phoenix Wright series reference
Go to The Royal Academy Island and give speeches behind the podium. Eventually you wull get a Figurine called "DJ Candy: Ace Attorney". The figurine is of DJ Candy behind a stand pointing in the famous "OBJECTION!" pose from the Phoenix Wright series of games.
Swordsman outfit
Press Minus to pause game play, then press Press Down, Up, Down, Up, Down, Up, Down, Up.
Tattoo vest
Press Minus to pause game play, then press C, Z, C, Z, B, A, B, A.
Your Own Island
Complete every task and go to Capital Island and watch credits.