Tom and Elizabeth board the subway train at a station named Union. The next station, the first where it fails to stop, is also named Union.
Just after the first car is uncoupled, we see an exterior shot of it running away, but its cab is at the wrong end. We can see into the car to a front-end window where the cab was, and the cab is visible at the rear. Next time we see the car, its cab is back where it belongs.
The type of plane that Merrick is on varies between shots (Boeing 767 on the ground, Boeing 747-200 in the air etc.)
When Elizabeth sticks a Post-It note with her phone number on Merrick, it reads 555-1234. When Merrick looks at it later, it reads 555-0199.
When all the passengers have been evacuated to the last car, we can see that there are about 50 of them. The information from the future says that 340 were killed in the single-train wreck.
When on the jet, the pilots wouldn't say lowering, they would be "descending"
The Thrill Seekers brochure shows the date of the Hindenburg crash as 17 May 1937. The Hindenburg crashed on 6 May 1937.
Date shown on Seth's digital wristwatch is Friday, June 16, 2000. However, that date was a Thursday. While character error in setting the time is possible, Seth is supposed to be an engineering genius.
A train car rolling sideways along four tracks plows easily through the three sets of columns between them. As these are sturdy supports for the roof, they should resist the car with much greater force, tearing it apart. And if so many of them did get destroyed, the tunnel should collapse. (Reused goof from Money Train.)
A crash that sends a railway car rolling along several tracks does not short out the power supply. Normal lighting is visible in the rest of the train as people are getting off it. (Reused goof from Money Train.)
When Tom and Elizabeth hide in a room in the train station, Tom quickly locks the door just before the female Thrill Seeker agent tries to open it. You can see between the door and the frame that the door is not locked.
Chicago subway cars are much shorter than depicted. (Filmed in Toronto.)
Is isn't explained why the temporal security agents sent only with a mission to eliminate Tom had futuristic WMD fire bombs ready to cause an event that should have happened without them after Tom was killed. They weren't able to time travel to get new equipment, and they didn't have time to build such advanced explosives out of contemporary materials.
The time-traveling tourist is very concerned with staying alive and returning home, and Liz is in the second subway car with his RTT. Yet, for no apparent reason, the tourist chooses not to leave the front car and dies in the crash.
After separating the front subway car, they should have at least tried the emergency brake cords in all the other cars. Each car has its own brake system.