what happens after the credits ?

nothing fundamental really, but it's a nice touch to the ending

It flashes back to the factory workers, who have been informed of the last failure. One of them calls her eastern european cousin, who has supposedly been in several wars. When he arrives however he seems to be totally lost and not able to speak french. While they are trying to (hopelessly) instruct him, he smashes his head against the wall to kill a fly and falls down unconscious. The movie ends with them deciding that it's probably better to find a different killer.

watch it again-
nicht zur Srafe, nur zur Übung.

The actor playing the cousin is Albert Dupontel, who was the lead character in the film Bernie (http://www.imdb.com/title/tt0115658/). When I saw the scene after the credits in Louise-Michel, I thought both movies were from the same director or something and this was some sort of cameo or a little wink to the audience.

Both movies are similar in tone, black humor... If you enjoyed Louise-Michel, you should definitely watch Bernie.