So we have the main side quest of gathering signatures from all the characters, and possibly the Hidden Mickeys if we could get a use from there other than a neat hidden detail. We know the signatures are the "armour" of the game, so what if the Hidden Mickeys were what you used to acquire more life in the game? After all I would assume we would fighting the bosses, and their attacks would cause life to be lost if hit.
Also open worlds tend to be immense, and along with a fast travel option I think there should be a travel option where the player would ride something. We could include trainable horses from Disney films throughout Frontierland/Fantasyland along with an unlockable Light Cycle from Tomorrowland, and an unlockable Magic Carpet in Aladdin.
You could unlock the Lightcycle by racing Rinzler, and beating him.
You could unlock the Magic Carpet by racing Aladdin, and beating him.
That woud leave a fast travel aka teleporting, any ideas?