Hal gives Dewey the program to "keep track of the laps." We see the first lap ticked. Then in two later shots (the program is in Dewey's hands then on the bench) half of the page is covered with marks. Then we see a clean page and the second lap ticked.
When Commandant Spangler is investigating the boys at the academy with his dog and finds that Francis is the one who has been smoking, the camera pans back to see the dog trainer hidden behind the pole, coaching the dog.