On Day 2 of this episode, Rob is wearing a small Cross on his suit lapel. It has no connection with the story. Dick van Dyke was an elder in the Presbyterian Church before becoming an actor.
Movies and television have often used the tactic of giving phone number as "555-" so people won't start calling actual phone numbers. LExington 2-1598, which came with Sally's gift, is a potentially real number. In the days when phone numbers incorporated descriptive names, Lexington was one of the names that was used in Manhattan, so this works out, since the show takes place in New York.