No one understood the deeply philosophical meaning of the film.
There is a character in American mythology called Reeper. It's a collector of souls. The one who comes right after death. The title of the movie is somewhat paraphrased - this is explained by the fact that 'The sense of smell is the last sense to die. When you die, you lose all your senses one by one, but your sense of smell is the last to die, and you still have a chance to smell death.
The heroes of the film have an accident and their whole life hangs in the balance. They find themselves at a crossroads - in the afterlife - and the whole movie is about the ordeal of souls. The souls have a chance to get back, and to do so they have to break out of the 'halfway house'.
The collector of souls hunts them down, because if he takes a soul, there's no going back. In the end, some will be saved and some won't. Time for the souls stops, it seems to them that they are saved from the ricker all night, but in fact seconds pass...