When Juan Sánchez Villa-Lobos Ramírez was killed in the prison, he had the Samurai sword with him, and Connor MacLeod ran out of the prison with his other sword. In the final fight, MacLeod has the Samurai again.
Throughout the high-speed subway scene, as the camera cuts back and forth from inside to outside the train, the passengers are flying towards the back of the train yet in one shot the passengers can clearly be seen sitting calmly behind Katana. In the same scene, the door separating the passengers from Katana is open in certain shots and closed in others.
Ramírez walks through modern-day Scotland, yet no one he speaks with is Scottish. The confused actor uses a Cockney accent, the man on the street complimenting Ramírez's clothes has an American accent, and the tailor has an upper-class English accent.
The subway Katana hijacks is traveling at over 400 MPH (235 KPH) when it crashes through the wall, yet stops only a few feet from the impact point, violating the Law of Acceleration. Additionally, the subway system would have protective barricades inside the subway or tunnel to prevent the crash.