Central Question left un-answered [SPOILERS]
Who hijacked the train? And why?
This is the central point of the story, and yet we don't get an answer. I understand that the writers wanted to concentrate on the passengers. OK, That's an interesting choice to make, creatively. But it does leave a very big hole in your film.
We do get one /hint/ of a clue: Carmichael's theory about driver suicide. But it's just that - one person's theory. It's plausible, but not certain. And even if it's true, can't we get a glimpse of /why/ the driver wanted to kill himself, and why in this way? What tipped him over the edge? How does he know so much about trains? What's the significance of Hastings? Why does he ask how many passengers are left? So many lines left hanging.
There are other flaws with this film too I'm afraid, but this is the big one for me. It's like Titanic without the iceberg!
_____________
"Maybe I should go alone"
- Quint, Jaws.