When detectives go to the park to find the panhandler who sold the missing baby's car seat, there a spread on the ground of other baby stuff that would have been in the stolen car too. There's a huge pack of diapers right there in the mix! I figured one of the detectives would surely mention that "if the parents already had diapers, why would the mom need to go to a store and buy diapers, which inadvertently gets the baby kidnapped?"
Review of Missing Pieces
