On some part of this site, it states that you will be able to encounter Jack Sparrow as a skeleton/undead pirate, which leads be to believe you will actually be fighting the undead pirates in the Pirates of the Carribean world.
As for the Huns, i'm not quite sure because so far, I believe Shun-Yu is the only human thought of to be fought in the Mulan world. However, the boss of the Mulan world is the Chinese Dragon, which is believed to be one of the first bosses you battle.
As for the Huns, i'm not quite sure because so far, I believe Shun-Yu is the only human thought of to be fought in the Mulan world. However, the boss of the Mulan world is the Chinese Dragon, which is believed to be one of the first bosses you battle.