The shadow scene in Peter Pan is a perfect example of the play's playfulness and cartoonish nature. For instance, the shadow, in contrast to the insubstantial shadows of real life, has an actual substance of its own. For example, Peter's shadow is snapped off by the window, and then Mrs. Darling rolls it up and stores it in a drawer without a second thought. This sequence of events is obviously impossible and goes against the laws of physics, as no one's shadow can be detached from his or her body and then rolled up like a yoga mat. However, this scene sets a tonal precedent for the rest of the story, showing us that the world of Peter Pan is one dominated by a playful rejection of the real world. As such, this shadow scene acts as a jumping off point that teaches us to adjust to the fantastical, child-like world of the narrative.
Peter Pan's shadow seems to symbolize some sort of tie to the human world of the Darlings. Mrs. Darling sees Peter's face at the window and when he flees the window snaps his shadow off. Mrs. Darling rolls it up and puts it in a drawer.
When Peter returns, he is unable to attach his shadow with soap and Wendy offers to sew it back on for him. Interestingly, Peter takes credit for Wendy's actions. After Wendy attaches his shadow, Peter thinks he has done it himself. "How clever I am!" he cries, "oh, the cleverness of me!" The shadow scene shows that Peter is still boylike, and very self-involved.