 Jules Munshin (qv) was terrified of heights. While performing on  the tiny rooftop during the song "New York, New York" the only way  he could perform the number was while one end of a rope was secured  around his waist under his sailor suit. The other end of the rope  was secured, off camera, to Stanley Donen (qv). And even so, alert  viewers of the scene will notice that during the scene Munshin is  almost always touching a wall or a prop or another actor.