Good zombie movie, except for one moment
When the people at the front of the train refuse to let the main protagonists in because they think they are infected. Come on, they have all seen what infected look like at this point and how fast they turn. They should have realised that the main protagonists were not infected after a couple of seconds. Not only that, but they then lock them away one car ahead, trapping themselves between real infected and people they think are infected. Dummies.