The Bills told ESPN that Hughes and Brown only missed the first team bus and that others were still leaving for the stadium. The pair decided to arrive in style instead. It certainly looks like they went with the Uber Black service, which is always a clean and comfortable ride.
It's unclear whether or not the team is totally psyched about this. Ryan typically allows his players a pretty long leash, but he's also not one for breaking up the team concept. Some coaches are overly protective of certain rituals, like the team bus ride or the hotel stay at home the night before the game.