Throughout Frank Sinatra's early career much was made of the fact that he was very skinny. They make a little fun of his weight in this movie. During the song "I Believe" in the gym Frank walks up a teeter-totter and, when he reaches the high end, it remains up until Jimmy Durante tosses him a baseball. When he catches the baseball the high end descends, implying that the baseball weighed more than Frank.
A girl is what you should get first. Then if you don't get anything else, you've still got her.
A running joke in the gym scene is that Frank Sinatra is so skinny that he needs the weight of a baseball to make a teeter-totter descend. It goes up and down as he and Jimmy Durante toss a baseball back and forth. At the last pass, the teeter-totter descends before Frank catches the ball.
Opening credits are shown over a drawing of the Brooklyn bridge.