When Don Draper enters his office to celebrate the Martinson's success with Duck, he unbuttons his jacket twice on his way to his desk.
In the Cadillac showroom, the salesman refers to the blue car as a Coupe de Ville, which it is not. A Coupe de Ville would have "Coupe de Ville" scripts on the rear quarter panels. This if further confirmed in the park scene showing the instrument panel and the open door. The door panel proves it to be a "Sixty-Two" model (not to be confused with the year). Cadillac Sixty-Twos were the least expensive Cadillacs offered.
In the park scene, as the family is leaving, modern street lights appear in the background when Don is throwing his can away.
While in the park, the Drapers appear to be playing a very strange version of checkers where the pieces inhabit squares of both colors.