On several occasions the detached car is a different model (Toronto class H-6) from what it is most of the time (class H-1). One obvious difference is the H-6's black rectangles around the upper headlights. The first instance of this goof is when the police tactical unit arrives in the tunnel. Also, just after the signals are set to red, the car number can be seen to be 5718.
When the train has been divided and the rear part moves backwards, the display at Command Center shows the entire train moving, leaving the place it had been vacant.
The Toronto subway cars used for filming cannot operate singly, so a two-car set was used. The single car supposedly detached from the front of the train can be seen on several occasions to be part of a train of at least two cars. The most obvious cases are when rounding curves: once when first moving forward after being detached, and later when Anthony has just figured out the hijackers' plan.
Mr. Green turns off the track power using a cutoff switch in the tunnel near the stopped detached car. But later the power is restored at Mr. Blue's demand -- by the Command Center.
The "motion detector" produces a radarlike display showing even stationary people. The last time we see this display, the direction of the refresh-sweeps is reversed.
Pelham trains usually take 35-40 minutes to get to 28th Street. In this film, the train left Pelham at 1:23 (presumably) but didn't get to 28th Street until 2:50.
Real New York subway trains always have the route number or letter displayed on the front.
The cars used on the Lexington Avenue Line (R-26/R-28/R-33/R-36/R62) do not have the same type of seating plan as those shown in the film.
Real NYPD motorcycles do not look like those pictured in the film, which are the same design as the ones used by the Toronto Police.
Such signalling displays do not show trains in a manner that allows their length to be continuously observed by counting the lit dots.
At 28th Street, instead of approaching the operator (driver) the moment the train stops, Mr. Blue remains some 100 feet away. Only after the doors have closed again does he begin walking toward the operator... as if he knows that the train will wait for him to start the hijacking.
Mr. Blue demands a plane with enough fuel for an "international flight." This is a very peculiar way to ask for enough fuel to reach Canada, but any other "international" destination would be much farther away; yet Anthony does not ask for clarification.
During the opening credit sequence establishing the New York setting, one shot of a subway station (just after the executive producers' credit) shows the Toronto station name BAY and its subtitle YORKVILLE.
On the section of the Lexington Avenue Line where most of the action occurs, there are four tracks side by side with local trains always running on the rightmost; the dialogue mentions the four tracks. Real-life local stations such as 28th Street have outside platforms with all four tracks between them. In the movie, only two tracks are ever seen except at switches, and 28th Street is shown with a central platform and the title train running on the left.
The line diagrams in the Command Center bear no relation either to the real-life configuration of tracks or to that in the movie; they appear to show the train on the middle one of three tracks, and this with no connection to the other tracks. The detail diagram displayed at one point on a video monitor is different again and also shows three tracks.
The relevant section of the Lexington Avenue Line includes curves sharp enough to have speed-controlled signals. As Mr. Green would have known, these cannot be cleared to green in advance of the train's arrival and will not clear if it is running away.
When the hostage says "Where are they taking us now?", a Toronto subway map is visible above the door behind his head.
The hijackers place what they call a motion detector in the tunnel, but it only covers one track and then only to rearward of the train.