In the situation with the police officer Zackgiebel is seen putting his briefcase in the car and left later without the bag. But in the next scene in school he has his bag in his hands.
The movie is set in Munich, as it can be seen by the uniform of the police officer and the license plate of Zackgiebel. However in Kosel's used-car shop cars with a Düsseldorf plate is seen. Usually cars which are bought should be re-registered to receive the plate of the town they are sold.
When Zackgiebel feels bad, the principal advised him to drink milk, as he things he is intoxicated. However milk is bad in this case, especially for an adult, as it brings the poison more into the blood and the intestine. In this case water is the better solution.