I will try to explain in my best english ( I am a french speaking person) the "unreal" issue of the movie. It's quite subtle but here what I understood of this story. Onoff is dead. He commit suicide (as we saw him do it) But before he can rest in peace, he has to remember and explain his acts and by the way his life and his identity to the inspector (an allegory for the guardian of The Heavens or any place you think we go after life..). Everything in this story takes place in the afterlife (except for the souvenirs of Onoff - is he On or off ?) . In this film, nobody is real. That's why everything is so strange. That's why the voice of Onoff cannot reach the woman he called at the end.
I hope this will enlight some of you.
I hope this will enlight some of you.