At the end of the race, a photographer photographs the winning horse and its owner using a camera of the era with a cloth hood. When the lens cap is removed, the subject of the photograph was required to stand perfectly still for several seconds while the camera collected enough light in order for the image to be sharp. However, the people in front of the camera continue to move chaotically and the cameraman does nothing about it. The resulting photograph would have been nothing but an unintelligible blur.
On the train, when the conductor collects Holmes's ticket, Holmes says "Thank you Inspector" instead of "Thank you conductor".