At their first stop, when Alex is trying to hitchhike, you can see him wearing some kind of sandals. However, when he returns to Marie and Vincent a few seconds later, you can see him wearing some old running shoes.
A Saab 900 plays an important role in this film. For shooting they used more than one car. There is a long scene where the protagonists are driving along the country shot from different angles in which you can see that one car does have a sunroof and the other does not. So every view seconds the "outfit" of the car changes.
In another scene the car gets stolen by cracking the steering lock. A Saab 900 does not have a steering lock.
Vincent has the ashes of his mother. In Germany it is not allowed to take the ashes of a deceased with you.