To see the hand you have to go to the beginning of the movie where the mom is doing laundry. right when the mom throws the laundry in the washer stuart little is in the clothes. when stuart is swimming around he tries to push the glass circular door open and when he puts his hands on the glass you can see a human hand. Its like they were filming and someone took place of stuart then when they went to do the graphics they put stuart over the man, but kept his hands.