When Tobias is talking with William, he grabs a highlighter and
a ruler to mark his textbook. In the next shot, we see him underline with a pen and the highlighter is nowhere to be seen.
As Xavier makes his way to his new job near the end of the film, he is wearing a coat, tie, and jeans, and he has his hands in his pockets. But when he gets there, he is wearing slacks that go with the coat, and he is carrying a briefcase.
When Xavier is going to the hospital for some exams, Jean-Louis shows a set of X-rays of the abdomen but it was an examination of the head.
When Xavier is at the airport getting ready to leave for Barcelona, he goes to talk to Martine and then returns to his mother and picks up his small backpack. He then goes back to Martine, without his backpack, returns to his mother and picks up his backpack again.
Next to the telephone, on the board indicating how to say a roommate is not there in many languages, the colors on the German flag are wrong. (It looks like a Belgian flag rotated 90 degrees clockwise.)