This is a "Wild Mass Guess" entry, where we pull out all the sanity stops on theorizing. The regular entry on this topic is elsewhere. Please see this programme note.
DoorMouse will become the Hero in a future episode!
If Umi Car was the Hero in The Great Umi City Race and then the Distressed Dude in The Umi Car Rescue, The opposite will happen to DoorMouse (he was already the Distressed Dude in DoorMouse in Space, he'll become the hero sometime in the future.)
I've thought about this for a long time, and wondered "Is Zilch a goblin?" Apparently, according to the other wiki. Our Goblins Are Different, explaining why Zilch isn't so greedy as your usual goblin.