From the excerpt, the mood is playful and comical.
This is true because the author revealed that they "pattered pitty-pat, pitty-pat each with feet and toenails, ears and hair, everything but tails,..." This shows that they were in a playful mood. Also, despite the way they pattered, when they got to the Philadelphia union depot, they had nothing to say. This also added a comical effect in the excerpt.
