Browsing through some DVD's Mirrormask just seemed like a gift to run across. I'll do a deeper post with screens and that once I've got it on my comp. But here is the themes from wikipedia, my interpretations will obviously be somewhat different!
"The character of the Princess (or anti-Helena) links to the Jungian idea of the 'doppelganger' or double; she is Helena's shadow self, the one that shouts at her mother in the beginning of the film, the side that she wants to apologize to her mother. Everything in the dream world has a double, sometimes evil, and this relates to the Jungian idea of the shadow self. The entire film is about the balance between the conscious and the dreaming, good and evil, black and white, dark and light.
As with other fantasy films about a young protagonist who enters a "dreamworld" that may or may not be real, MirrorMask contains a number of visual cues that link the real world with the supposed fantasy world, some of which are used in the opening sequence and foreshadow events that will take place later film. A clear example is in Helena's introduction, when she is seen playing with a white sock (the White Queen) and a black sock (the Black Queen). Helena can also be heard saying, "I'm a very important man", a line that the character Valentine will say repeatedly later in the film. Various objects in Helena's circus trailer and apartment room also reflect objects and places that Helena would later visit in the City of Light and Land of Shadow."