Well, it has something to do with the men on the Empress, and since Keira is dressed in that robe thing, it's sometime after they go to Singapore.
Will's costume is really interesting and I'm not sure if it's a good or a bad thing he looks more like a pirate. On the one hand, it'll be exciting seeing him accept his fate, but on the other hand, what does that entail for Elizabeth? I can't see how that would suddenly make him more attractive to her. In fact, that would be pretty lame if he started acting more like a pirate and then she switched teams yet again. You know what I'm saying?