In anticipation of the launch, the Japanese authorities posted several safety advisory statements warning of possible dangers of playing the game while not paying attention of your surrounding.
It was only an hour into the launch when the first reported injury of a student falling down some stairs being rushed to the hospital with a gushing head wound. Soon after a number of reports of other people falling or slipping while playing.
Japan with it's high population and dense urban areas with a variety of transit can be an obstacle course on its own even when you are paying attention. So this game could be a real test for a society that survives on constantly being on the GO.