As they race the ransom money to the station, the police motorcycles all sound like high performance four-cylinder Japanese machines. They are clearly all twin cylinder BMW "R" series bikes. Fast enough - but quite different sounding.
When Garber is instructed by Lt. Staley in the use of the Walther PPK .380 he is told that the safety is on when the lever is up and off when it is down. This is the opposite of the safety's actual operation. When the lever is up, exposing a red dot, the safety is off. When down it is in the SAFE position.
In the first scene, when we see Garber talking through the microphone the very first time, he presses the red button. From that time on, we see the characters pressing the blue one to use the microphone.
In the opening sequence Garber is at the controls with a napkin tucked into his neck and he is eating, next we see him without the napkin having a cup of coffee. In the next shot he has the napkin back in.
When Garber is first being rushed to the helicopter and his phone rings, his hand is about to grad the door to enter. The next shot shows him much further away from the doors answering his phone and he asks, "Should I wait here"?
In the shootout between Erim and Bashkim and the police, the two bad guys get shot several times and you see the blood splatter from their bodies, although you have seen the two bad guys wear Kevlar vests in the train where they zip down their shirts.
When the train is going really fast, you see a quick shot of Shea Stadium (blue facade showing a gate). Shea Stadium was located in Queens (it was demolished before the film's release), and the 6 line does not enter Queens at any point along the line. You also see a quick shot of it passing a 7 train which is the Flushing Line train that runs to Shea Stadium.
The scene in which Ryder forces his way into the 6 train (Bronx - Manhattan) is supposed to be North of Grand Central - 42nd Street Station. In fact the station that is shown in the movie is actually the Grand Central - 42nd Street Station for the 7 train (Manhattan - Queens), a station where the 6 train never runs.
The hijackers make their escape through a secret tunnel connecting the NYC subway system to the Waldorf-Astoria Hotel, and this occurs around 33rd St. In fact, the Waldorf-Astoria is between 49th and 50th Sts; moreover, there is no such tunnel, although there is a tunnel connecting the Metro North Park Avenue train tunnel (not part of the NYC subway system) to the Waldorf-Astoria.
From the time the hijackers leave the train until just before the brakes are tripped, every station displayed in the control center to monitor the train's movement is in Manhattan and underground. However, numerous shots show the train above ground.
When Ryder and his men make their escape in the Subway they travel downtown. When they stop in lower Manhattan, when they exit the Subway to the street they are now on Park Avenue in the 40's uptown and to the east from where they stopped.
When the subway cars are stopped at the beginning they are supposedly just north of 42nd st. Then they split the train and back up the other cars. Then the passengers walk to the Grand Central to exit. They would have to be at 51st st station.
You cannot actually have a "2-way conversation" on a 2-way radio at the same time, meaning one person must speak at a time, release the talk button, and then must wait for a reply. During the movie, on several occasions, you see conversations with the subway car and central command speaking over each other like in a phone conversation. This is not possible using a 2-way radio.
On the bridge to Brooklyn Garber walks through subway tracks and onto the pedestrian area of the bridge through an unlocked gate to get to Ryder. In reality this would be locked by a chain and padlock.
On the exterior of the train, the car number was 8837. But in the motorman's cab, the car number was 7426. For the R142A Subway car, the numbers would be in the 7400 number range. 8837 would be in the 8800 number range for the R160B Subway cars
During the hostage situation, the kidnappers have net connection to buy stocks and watch the news about the incident. The girlfriend of George shares the the web camera feed online, so that the news stations can show them. But the kidnappers never see the feed on the channels they are watching. However, whichever station the girlfriend contacted may be keeping the feed as an exclusive, or the hijackers may not have watched that one channel out of the numerous options available.
On the train there is a boy who has his girlfriend on webcam via laptop. Midway through the movie the laptop's battery dies and shows 0% power left. However closer towards the end the boy is somehow able to turn on the laptop, reconnect to the webcam service, and even utter a few words before it cuts to another scene. With 0% battery power this would be impossible.
When Garber's wife is calling him on his cell phone, we can see the caller-ID on its screen that says "Home". We can clearly see the word "zoom" under the caller-ID, showing us that it's a picture preview and not an actual income call.
When the ESU sniper takes his position in the tunnel, he operates the bolt action on his rifle. After Ryder shoots Wallace you see the sniper operate the bolt action once again which would have ejected the bullet, but it did not, meaning the rifles magazine was empty.
The goof items below may give away important plot points.
Near the end of the movie, Garber chooses to go home by riding the subway. He is then seen staring out of the window, which is very wet from rain. However, before and after he gets on the subway, it's a bright and sunny day and everything is clearly dry.