Acting for Two: Stephanie Leonidas is Helena and the Dark Princess. Rob Brydon is Morris Campbell and the Prime Minister. Gina McKee is Joanne Campbell, the White Queen, and the Dark Queen. Jason Barry is Valentine and his equivalent in the human world.
Dawson Casting: While it's never made explicit what age Helena is supposed to be, it can be assumed to be her mid-teens. Stephanie Leonidas, however, was in her early twenties when the movie was shot.
Development Hell: Supposedly there were plans for a prequel in manga form that has yet to be published.