The detectives find the seaside villa that had been used as the criminals' hideout, but they find no clues to the kidnapper's identity and embark on a long and difficult search for him. It is never explained why they don't simply ask the owner of the villa who rented it. However, this would be pointless because if the criminals are as smart as they seems to be they would just not use a real name.
The story occurs in midsummer. This implies that Mt. Fuji has no snow. Since the location filming was carried out in winter season, the top of Mt. Fuji is very white. Some film critics mention that this is almost the only mistake they can find in the film.
When the police is reviewing the footage from the train (where the kidnappers retrieve the briefcase), the camera rotates 180 degrees backwards and, despite it having been recorded from the cabin, the view is never blocked.
When Tokura describes the evidence found at the cottage to reporters and they ask if the neighbors will give away his proposed deception of the kidnappers, he states "It's a new development with few houses." However, when the boy, his father, and the two detectives are looking around the yard there is visible aging of the paint on the fence, siding, and window casings indicating that the house has not been painted in a few years.