 DATE: When Kay leafs through Bernstein photo album, there is  picture of a New York City taxi with a rectangular roof light which  displays not only the word "Taxi" but also whether the taxi is off  duty and its medallion number. Those signs did not come into service  until the 1960s. In the 1940s, when the movie is set, New York City  taxis used a variety of curved roof lights used in most other  cities.