How does David Henry Hwang use imagery in M. Butterfly?

In the play's final scene, Gallimard dresses up as Madame Butterfly in order to reunite with his "perfect woman." After dressing himself, Gallimard "plunges the knife into his body, as music from the "Love Duet" blares over the speakers...Then a tight special up [spotlight] on Song, who stands as a man, staring at the dead Gallimard."