In the beginning Malcolm and Reece are watching TV, when Dewey steps in front of Reece the TV in the background is off but you can still hear the TV on.
Lois and Caroline are sat down with hot drinks. In one shot, Caroline lowers the cup to her lap. Then its raised to her face then on her lap again.
Francis feeds a mouse to a snake (we hear it squeak). When we next see the snake the bulge of the mouse in the snake's throat/body is not visible.
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.
(At about 3m 27s) When the billiard ball shot by Francis hits the senior cadet's head, you can briefly see the stage crew hand on the right side throwing the ball.