The Polar Express is about faith, and the power of imagination to sustain faith. It's also about the desire to reside in a world where magic can happen, the kind of world we all believed in as children, but one that disappears as we grow older.
I wasn't aware of my dad being an actor when I was young. I remember there was an Australian children's entertainer on television called Ralph Harris and when I'd say my father was an actor, kids would say, you know, 'oh, is he Ralph Harris?' And I had to say no and then they would lose interest.