Adventureland/WMG

The final scene is just a fantasy of James' while he's on the bus.
The odds of him running into someone he knew as the first person he met in New York City of all places is astronomical, obviously. Plus the whole scene has a bit of a dreamlike quality to it, the rain falls in a very Hollywood romantic way and the overall atmosphere is just too perfect. The scene of him on the bus is the last scene of reality in the film.