Revealing mistake: When Mr. Green pulls out of 28th Street, we see him disengage the "Dead Man's Feature" (by pressing down on the throttle with his hand). However, he does not actually move the control lever to make the train move. In that position, the train is at "idle" and will not accelerate.
Revealing mistake: At the end of the film when Mr Blue electrocutes himself, he falls forward to the floor. As he falls you can see him move his eyes to see where he is falling.
Revealing mistake: When the men get off the train and it starts racing down the tracks, the hostages start getting frantic including the two Hispanics. In one very brief scene you can hear the Hispanic man tell the woman in Spanish to calm down but his lips aren't moving.