As the PP have said, having the Fantasmic show just after closing is not uncommon. I think they do it to help distribute the bus loads (i.e., one pulse at closing and another after Fantasmic ends). In terms of the buses, I agree that the "best" option is going to be sit as far back and as close to the exit as possible. As soon as the show ends, head out to be ahead of the crowd. From there, just head to the bus stops like normal. In my experience, while the crowds will be heavy after the show ends, it's not like folks are lingering. There really isn't anything to do or see, so people do head out at a fairly good/normal pace. So even if you're stuck int he middle of the crowd exiting the theater, it isn't going to add a huge amount of time to get back to the bus stops. The lines at the buses are a different story...