IMDB's triva section (don't read it) appears to indicate it had a different ending at the cinema? The ending appears as one of the cut scenes on the DVD, and it was rubbish. It would most definitely have ruined most of the movie.
I thank whoever is responsible for putting the good, ultra harsh, ending and required subplot on the DVD. An Amazon review indicates the cinema had the shite ending, while the DVD I watched was a "special edition" with the better ending.
Good for me.