Where is Cirno's shadow? If you look at the railings you can see that the sun is shining from an angle and her head is at a similar height yet she does not cast any shadow at all except on herself.
I am guessing the artist forgot to fix it or tried to but felt that would come out worse to wear. Though I would have wished he changed the shadow of the railings so it wouldn't be at such an angle in comparison to Cirno's shadow.