Continuity mistake: After Melanie's "plan A" failed since the train is not at the station the group fights its way back to the prison. During that fight they kill quite a lot of the possessed miners. But in one of the following scene when those freaks assemble in the streets and walk to the prison there are only four or five bodies lying around.
Continuity mistake: According to Ballard at the beginning, a captain wears two bars (as per modern US insignia). However, Braddock wears two bars and her rank is given as Commander throughout the film.
Continuity mistake: Early in the movie, when Ice Cube is accidentally released by the two rookie cops, Natasha Henstridge offers herself as a hostage to obtain the release of the blonde rookie. Ice cube switches hostages and holds a knife to Natasha's throat. Right as she slips out of his hold, the knife pushes against her neck and for a split second you see the blade bend.