During Stefan's drive through the countryside with Jennifer, the license plate on his car changes.
At the ballet, Count Stefan and others in his box use the opera glasses to look down at Jennifer in the audience below. The first shot through the glasses shows her not looking straight up at Count Stefan, but to her right, even though they have acknowledged each other. In subsequent shots through the glasses, the perspectives are far too low and to the front of Jennifer to be from the box above.