Even by Will Ferrell's standards this is a stupid mess of a film, enlivened by a truly stupid chase at the beginning of the movie involving a really strange looking New York open top tour bus, which is hit amidships by a flying car:
The bus looks suspiciously short and there doesn't appear to be a staircase. The front is a giveaway: American builder Blue Bird built a version of the UK Dennis Dart, the Ultra LMB, and this one was mocked up as an open top double decker - hence what looks like a Plaxton Pointer front! At one point The Rock takes the wheel to help hurl the car at the bad guys - yes it's that sort of a film.
The closing scene of the movie features a much more conventional RTS transit bus, albeit at a distance:
(thanks Keith)