Revealing mistake: If you look at the missing part of the bridge, and look at the shadow underneath, the shadow is of a full bridge.
Revealing mistake: After the first bus explosion when Jack answers the phone, he looks at his watch, which shows 8:05 a.m. If you look closely the watch is on alarm, not regular time.
Visible crew/equipment: When the bus is about to jump the bridge, you can see that the bridge is flat, apart from the broken part, but when the bus jumps over the bridge, there's wood and stuff piled up at the end, making it "kick".
Continuity mistake: When Jack tries to get on the bus on the highway, he hits the door window and breaks it with his elbow. Later, when he finally catches up with the bus and gets on from the moving car, the door window is intact. Several times later it is visible, no break. Then later, when the bus is on the freeway, the glass is shown broken again, but in a different pattern.
Visible crew/equipment: When the bus is turning right off the freeway at the start of the film, one shot shows a camera mounted on the side of the bus.
Other mistake: Towards the end when Dennis Hopper is on the subway train with Sandra Bullock, he has a gun in one hand and the detonator in the other. However, when the camera cuts to a close-up of him handcuffing Sandra to the pole, both hands are empty. If he took his hand off the detonator, the explosives attached to Sandra should've exploded, but they didn't. In the next shot, both items are back in his hand.
Revealing mistake: When the train is sliding along the ground near the end, there are sparks coming from the underneath (supposedly where the metal scrapes the pavement). Look more closely, and you can see that the sparks are coming from a bit of the train that's not touching the pavement anywhere.
Continuity mistake: After Keanu commandeers the civilian's car, breaks off the door and jumps to the bus the civilian loses control and heads for the water barrels in front of the divider. Right before he hits you can already see water all over his windshield.
Continuity mistake: Just before the first bus explodes, Jack leaves the cafe and puts his coffee cup onto the top of his car. When he runs back to his car, the coffee cup is different as well as in a different position.
Revealing mistake: During the rescue of the elevator passengers at the start of the movie, when coaxing the last woman out, there is a shot of the interior of the elevator where you can see the ground through the hole in the elevator floor, even though the elevator is still meant to be on the 22nd floor.
Continuity mistake: When the cops arrive at Payne's house, the front passenger door of the silver car closes. However, in the next shot it is open.
Continuity mistake: Near the end of the film when Keanu Reeves and Dennis Hopper are wrestling on top of the subway, if you watch Keanu's left wrist you notice he is wearing a watch. Yet throughout the scene it is obvious that the stunt double has no watch, because in the extreme action scenes, there are no signs of it anywhere on his wrist.