Deleted Scene: Not vital to the plot, but one scene that was cut was an alternate introduction of the protagonists to Masters Croc and Ox. Originally, they were going to all meet at a street fighting ring, but was cut for various reasons. The design of the jail strongly resembles the arena that they were supposed to fight in, and the whole scene was later recycled into the bonus DVD Secrets of the Masters, which talked about Croc, Ox, and Rhino.
Working Title: First, Kung Fu Panda 2: Panda-monium. Then Kung Fu Panda 2: The Kaboom of Doom. They eventually went with a simple 2 at the end of the original title.