The Missing Reflection
Shadows and reflections; these two seem to be the downfall of animators everywhere. When it comes to reflections, we actually get it. It’s not easy to illustrate something that’s sort of transparent but still visible.
So maybe they just didn’t bother in this Toy Story scene. Or, they forgot. Because you may have noticed in that scene where Ham and Rex click through the channels on the TV, and the TV goes dark, neither of the two have a reflection in the TV screen.