After the crash the radio announces that over 30 have been killed but later the paper states 20 killed.
The train stops unexpectedly when the communication cord is pulled. A goods train subsequently collides with it. A member of the Railway Accident Investigation Department believes that the pulling of the communication cord caused the collision. While rear-end collisions on railways are not unknown, railways have complex systems to prevent them. These systems too may fail, but no railway official would believe that an unexpected stoppage would cause a collision.
John goes to a hotel and is given a key to room 40. Walking along a corridor past rooms 42 and 39 to room 40. It can be seen that there's only a short space between the doors yet when John goes into his room it can be seen that the room width is wider than that between the doors.
Towards the end of the action, Jerves Wilding says that he checked in to the hotel under the fictitious name "Denny" taking up a reservation that John North had made. WIlding could not have known the name of the hotel, nor of North's fictitious name used for the booking.