So - in AB, if you jump just right (or just wrong) - you can manage to get yourself stuck into the edge of the platforms. Your feet wedge themselves a bit below the actual "surface" of the platform, stuck inwards a bit. And then you're stuck and can't do anything. Luckily, if you follow someone else, you'll "pop" out of your position and be free.
No big rush - there's almost always someone there to be a brave rescue ranger, but something for a lazy afternoon. :)