During the task, Jack used his mobile phone to call his father, not to tell his father that he was "alive," but to tell his father what he had always wanted to say as his friend. Although this world is not real, he still does his best to avoid causing a second blow to his father.
In addition, Jack and the heroine walked off the train holding hands, and life was re-given with meaning instead of time being re-given with meaning as the doctor said. I think this is what Duncan wanted to express by borrowing the source code.
View more about Source Code reviews
