Each time Violet gets a close up, you can see that her ribbon isn't in the same place.
Most of the teeth in the Tooth Fairy's castle are molars with intact roots. But most of the teeth children lose are incisors and canines and the few molars they lose don't have roots attached.
When Death and Albert are walking through the streets only one of Death's eyes has its blue glow.
In the last scene, when Death is looking out of the window, reflections of modern street lights can be seen on the glass.