This film was intriguing and entertaining. I agree with all the previous reviewer said, but wait, there's more!
After thinking about it, sleeping on it, I came to realise why it bothered me so much.
A prophetic film for these times, because as (nearly) all of the characters in the closed community of the train are conspiring in a lie, while Iris asserts the truth she knows, so in our times - the western "progressive" community is conspiring in a lie that leads to death. That is, the lie that people can change sex.
Another interesting idea was the theme throughout of music, styles of music and the meaning of music. Why was the singer strangled? Just an amusing reference to the horror genre? And the all important code was embedded in music. It still is.