 At the beginning of the film, Malmberg (a Swede) becomes ill after  having to drive on the right side of the road in Norway. Today both  countries drive on the right. In 1967, Sweden switched to the right  because making two versions of cars like Volvos and Saabs for  domestic and foreign sales was inefficient. Also, there are many  unguarded, unmarked border crossings points (unlike the crossing in  the film); people would not realize which country they were in and  sometimes ended up driving on the wrong side.