Other mistake: In the scene when Will finally stops the train, his phone beeps letting him know he has a missed call. He looks at his phone and sees the photo he presumably has associated with his wife Darcy. Later on, during the press conference scene, right after the first part of the dialog between Will and Frank about "corporate", there is a shot of Darcy at the press conference. This exact same shot was the photo used in Will's cell-phone earlier on. (01:30:20 - 01:31:40)
Other mistake: In the scene immediately after the locomotives that were trying to slow 777 get derailed and blow up, the next scene immediately shows Colson in the cab of his train exclaiming about the explosion which he sees just over the tree tops. Impossible. Colson's train is still miles away on the head on collision course with 777, and Colson could not possibly see this explosion, let alone as if it was just around the bend.
Other mistake: When the runaway train is about to hit the rail car, the rear bogey on that rail car is not on the tracks.
Other mistake: When 1206 is tracking close to 777, Barnes asks Hooper how far away 777 is from 1206. Hooper replies "one and a half miles, and gaining." Barnes indicates that 1206 just passed mile marker 57. Shortly after, Hooper states that 777 is at mile marker 61. This would make the distance between the two at minimum 4 miles apart.
Suggested correction: Not necessarily. Some engines may not have a rear cab access (like Frank/Will's engine had). And even if the rescue engine did have a rear cab access 777's engine only had a side access stair which at the speed it was going is more difficult to climb over from the engine in front of it.
Actually 777's catwalk goes across the front, from side stair to side stair, but someone would have to leap over a rail or a chain to get onto it from the other engine. Why would there be stairs on the right side unless there was a catwalk to get to the door on the left side?