Amy works at a TV station on Long Island that is on channel 3. The New York City television market already has channels 2 and 4, and having a channel 3 among them would cause all three's broadcast signals to interfere with one another. The only back-to-back channels that could exist in any TV market (or close by markets) on either VHF or UHF is 4 and 5 due to a barrier that prevents each one from interfering with the other.
Sarah (Maggie Q) works at Fields Market. The show takes place on Long Island in New York. Fields Market does not have a location on Long Island. The only known location is in West Hills, California.