 You can check any of these possible errors but you cannot check them all. You cannot discount these pedestrian possibilities as science fiction. These are exactly the sorts of possibilities we check when plans go awry. For instance, you think you know that you have an appointment to meet a prospective employer for lunch at noon. When she fails to show at the expected time, you backpedal through your premises: Is your watch slow? Are you remembering the right restaurant? Could there be another restaurant in the city with the same name? Is she just detained? Could she have just forgotten? Could there have been a miscommunication?