He receives a cell phone call while inside a total metal cage, the bank vault - which would block the signal.
At the end of the movie Adrien Brody's character goes to see Caroline "in a new life." His car has New York plates but another state's registration sticker and no inspection sticker at all - which is required in NY.
The taxi that drops Porter and Caroline at her apartment when they duck out of the party is not a New York City taxi. Its roof light is wrong, its medallion number is wrong, there is no medallion affixed to the hood of the car, and there is no fare information on the rear door.