Other mistake: Whenever Verne is inside his shell, he has a tail (and references to it "tingling" are made throughout the movie), however, when he is out of his shell he has human-style buttocks and no tail.
Other mistake: When Lou climbs the tree, to tear off some bark to eat, the bark should stay on his belly but it is on his back when the kids are complaining.
Suggested correction: He rolls backwards and his back grabs the bark off the tree.