In a scene in which one of the reporters gets into a taxi at night in Washington, D.C. the light on the top of the taxi goes out after the door is closed.

In New York, at that time, when the driver pressed the arm of the meter down to start it, the light would go off to show that the taxi was not free.

However, in D.C. there were no meters in taxis, and the light wouldn't have gone off.