Hello my son watched this movie in 2007 and he can only remember serten seens and he wants to watch it for his birthday here is what I know:
It is animated
It starts off with the main characters (kid) bed grows long legs and carrys him down the street then some magical person meets him in his blimp and they set off to a magical land. then they see huge red mushrooms.
later they accedently open a door the king of the realm told them not to what ever the needs and a black goo spreads out and locks the king up or something
anyway thats all he remembers please get back to me soon