At various stages of the discussion between Peter Campbell and his wife regarding the purchase of their co-op apartment, they discuss down payments and mortgages. In 1960, the buyer would have been expected to pay the total amount up front for a co-op.
Pete and Trudy's new apartment is at Park Ave. and 82nd. At the end, Pete looks out the apartment window on a view of Central Park that is impossible from that location. He's looking from the top of the Park, directly south, as though he's on 110th (or higher) between 5th Ave. and 8th Ave. (which encompass the width of the Park). With this impossible view, Pete takes in a nighttime skyline that includes the Chrysler Building and the Empire State Building; this is the New York equivalent of "all windows in Paris look out on the Eiffel Tower."
Pete & Trudy's new apartment is referred to as being at 83rd Street and Park Avenue, yet the interior shots of the apartment show that it is clearly of post WW2 architecture. All of the residential buildings at that intersection are of pre-WW2 design and construction. (Pre-war apartments were generally considered to be much more desirable, especially along Park Avenue.)