Short and sweet
Although this was relatively short I still was amused by it. I've seen it happen so many times on all sorts of online websites.
Some things I liked:
1. The graphics - although simple - were pleasant to look at. The smiling people amused me.
2. The sound - I liked the angry over the top yelling for the bad person and the happy music for the rest.
3. The message - Just how simple it is to derail threads.
A suggestion, though. It could have been a bit longer. I realize the purpose was to be a bit short. But perhaps some conclusion would have been nice. Maybe seeing everyone dead or gone from the train. Or maybe seeing what happened to the guy. I realize you can't change it, but for future submissions I would recommend including an ending =)
So ya, good submission and thanks for the amusing movie. 9/10