 During the circus montage at the beginning of the film, there is a  brief shot of a hand balancing and twirling a set of four crystal  balls. This art is called Contact Juggling, created by performance  artist Michael Moschen (qv) and originally debuted in the  Jim Henson (I) (qv) film _Labyrinth (1986)_ (qv), which in part  inspired this film.