Combination of wrong path and untrustworthy troop.
This should have been the Holywood's bad boys film. I mean the big cast names are expected like the earlier films of QT, or especially like 'The Departed'. There were many who dropped out of it for various reasons prior to the production commence, although this cast did a great job. In my finding I blame for the screenplay. It was a good story, but the first half was not very interesting compared to the next half, which was so brilliant, especially towards the end, mind blowing.
It was a multi starrer film, only that's much I know, but... read the rest.