I've already made a comment about this earlier in the thread, but it appears no one saw it. This was footage from last year's Comic Con panel and since then they changed his appearance for reasons only known to the film makers. That's it. They might say why in a Q and A with the director or cast sometime down the road or even on the "Making of" on the Blu Ray.
Everyone does realize that these CG models/textures/backgrounds etc always get re-worked during production, right? I work as a 3D artist and we're constantly messing with our stuff or have to make big changes on a minutes notice because someone higher up didn't like what they saw. As others have said, maybe they couldn't get the snout look to work correctly if he had dialog he needed to say, thus the more human face/mouth.
But we do know that the leaked comic con shots were from the bathroom scene, as the description of it from people who saw it say he comes out of the floor of a girls bathroom stall and scares the crap out of those two girls. In the trailer, we can see him climbing out of a hole in a bathroom stall, so put 2 and 2 together.
