The New York City telephone in the opening scene is incorrectly dubbed with the "Ring-Ring, Ring-Ring" double cadence of a British telephone. A standard American landline phone (to this day) uses the cadence of a two-second ring followed by a four-second pause.
The scenes inside Grand Central Terminal show the iconic station in its current restored form. In 1977, when the scene takes place, there were billboards all over the inside and the ceiling was covered in a layer of grime so thick that the famous mural could not be seen.
The screenshot of WASHINGTON, D.C. superimposed over the hotel building shows the modern cars such as 1995-1997 Lincoln Town Car along with the modern newspaper vendor design that wasn't in use until 1990s.
In the 70s, NYC had a problem with graffiti on the subways, as seen when in an earlier episode. The subway car is much too clean for the period.