In the scene where Tom Hanks is visiting Meg Ryan, she is in bed and he is sitting on the edge of the bed talking to her. Right before he gets up for a moment to pull up the covers over her, (now, turn the sound up for this one) he actually passes gas. You can hear the little "pop", he starts to grin and then probably realizes that the director is going to just continue on with the scene, so his grin fades and the scene goes on. I replayed this over and over. It really happened.