The difficult thing was how to really make this, but without people knowing. Their work paid off with a dense plot and multi-dimensional characters that effortlessly sweep you into the story. Any mistake can kill you. It's very risky. If you edit badly some little scene.
All decisions are important.
How you end or how you begin. The music is a little too much or not enough. All the decisions are very tense. The movie opens in the middle of a car chase, to which we return throughout the film. Everyone's destiny is caught up in the resulting crash.