Continuity mistake: When Fox is driving the Corvette during the scene where the assassination in the limo takes place, the shifter and console seen are that of the Viper she was driving earlier in the movie, and not the Corvette she was driving in that scene.
Continuity mistake: In the scene where the Corvette goes head to head with Wesley's Mustang to flip over the limo and kill the target, while the Mustang flips in the middle of the air, it's going clockwise. But in the landing scene right after, it lands in a counter-clockwise movement. We actually see it landing while spinning clockwise, but the camera is now behind the car, which should reverse the way we see it spinning. For example, if you upturn a bicycle and spin its wheel clockwise, if you move around to the other side of the bike, it will now, from your new perspective, be spinning counter-clockwise. It's difficult to see as it happens very, very quickly, but it is very much noticeable that it lands while spinning in the opposite direction.
Continuity mistake: When Wesley slices the Butcher's neck, the far angle shows that he cuts him on the left. But when the close-up comes, it's on the right side of the neck. And when Fox is beating Wesley up, as she punches him, the close-up of the brass knuckles shows them on her left hand when the wide scene showed the brass knuckles on her right hand.
Continuity mistake: After Wesley kisses Fox in his old apartment and sees his father and the bullets collide, Wesley chases his father up some stairs and starts shooting at his father/the screen with his left wrist under his right firing hand. When it shows him from behind he is holding the gun with two hands. When you see him from the front again he is holding the gun right over left hand again. (01:05:25)KyHole
Continuity mistake: Cross shoots his son in his left arm, close to the middle biceps area. When he is in the healing pool and he takes out the bullet, it is much higher and closer to the deltoids/shoulder. (01:06:00 - 01:08:00)
Continuity mistake: In the scene where Wesley is chasing Cross on the train through the tunnels, where the back of the train falls off the bridge; the last car is shown exiting the tunnel, and about four seconds later, begins to slide off the track and pulls the second car with it. They cut back inside the train to show you people falling and screaming, and the next shot on the exterior of the train, you can see the last car is exiting the tunnel again, and the two cars ahead of it have fallen off and are what's beginning to pull the train off. (01:15:55 - 01:16:14)