California Doubling: New Yorkers will recognize some shots as having been filmed in the city, however the subway cars, tunnels, and stations are clearly not in New York. Much of the action takes place on a car that explicitly says "GREEN LINE" inside. New York does have subway lines colored green, but all routes are identified by their letter or number, rather than the color.
Fake American: Tony Curran, a Scotsman, does a pretty good American accent as the train conductor.
Promoted Fanboy: Kitamura is a huge horror nerd, and was reading Barker's work — translated into Japanese — when he was a teenager.
Screwed by the Network: The movie was utterly fucked over after Lion's Gate came under new management, and the new CEO deliberately killed off all the projects his predecessor was championing. After repeated attempts to make the movie "appeal to a broader audience" were fiercely rebuffed by Barker and Kitamura, they decided to technically honor their contract and release the movie in 150 bargain theaters in the American Southwest. There was a campaign by Bloody-Disgusting and a few other horror sites to buy as many tickets as possible to make a point, but it was too little, too late.