Okay Ifound This easter egg while playing on nepal. When you get to the part where the bridges are falling down the biggest one that falls down, fall down to the bottom of the pit and look around until you see a cave. You can go in it if you are playing free play. When you get in he is freed. Find him ,C-3PO, R2D2, Chewbacca, and Princess Lea to unlock Han Solo as a playable character.