Shirley Jones learned she was pregnant with her son Patrick once filming had begun. She met with director Morton DaCosta over lunch to inform him of the situation. Her concern was that she would begin "showing" during its filming. He assured her that they could work through it with costumes and also by filming her from the waist up, if necessary. He did have one request, that she tell no one about it. Robert Preston did figure it out before filming had concluded, when Shirley's character, Marian, and his character, Professor Hill, kissed for the first time in the romantic footbridge scene. He leaned in for the kiss and jumped back, asking her, "What was that?" to which she replied, "That is Patrick Cassidy! Say 'Hello!' " Years later, her son Patrick had the opportunity to meet Preston. He walked up and introduced himself saying, "Hello. I'm Patrick Cassidy." Preston replied, "Yes, I know. We've already met."