The Manhattan building they all lived in before their move to Westport, Connecticut was addressed at a fictional 623 East 68th Street, on the Upper East Side of Manhattan, which in reality would be located in the East River. However, E. 68th Street in Manhattan only goes up to 600 – which means that the Ricardos’ building was in the middle of the East River.
At the time, most television shows were broadcast live from New York City; but because Ball was pregnant, she and Arnaz insisted on filming the show in Hollywood.
During the course of living in their New York apartment the Ricardo’s had three different telephone numbers. The first was MUrray-hill 5-9975, the second was CIrcle-7-2099, and the third was MUrray-hill 5-9099. In actuality these numbers were unused telephone numbers of the New York Bell Telephone Company. When the numbers were entered in to service the Bell company would advice the shows producers and give them a new number to use. Murray Hill and Circle were also actual call names used in Manhattan at the time.
The back door so much used in both the Ricardo’s and Mertz’s apartments were in actuality a common trait of older buildings in Los Angeles and not of those in New York
