When the Detective first calls at the Grange the Butler greets him with "good morning" even though the detective had previously arranged to call at 3pm that afternoon.
When the Detective first meets one of the sisters his pocket handkerchief assumes numerous different positions despite it being only one scene.
When Inspector Marley agrees to visit The Grange he promises he will be there at 3 o'clock but when he gets there, the butler wishes him good morning when he opens the door.