Monsters, Inc. - A Toy That Transforms Itself?
As the very first scene unfolds, we see the "mechanical" boy's room in the dark, just before the monster comes through the closet door. During this take (from above), we can see a toy train laid out on the floor, next to a skateboard. Once the monster makes it into the room and is scared by the boy, the toy train has mysteriously been replaced by a handful of jacks.
See the examples below and post your pictures
|Initial scene, the train and skateboard before they disappear
Monsters Inc. - DVD