Toward the last 15 minutes of the film Richard dreyfuss's character, in order to make amends to Marsha Mason and her daughter, hires a Central Park horse and carriage.

He first has the driver pick up the girl at school, and then they go on to pick up Mason at home.

Right after he picks up the girl, the two are seen sitting opposite each other in the carriage's rear, talking.

Next is a medium long shot from above showing the carriage progressing down the avenue.

Only there's clearly NO ONE sitting in the back seat