Other: In the scene where Ecks is chasing Sever, you see Ecks put a shell into an open chambered shotgun. This means that there is only one shell in the gun. A moment later when he yells stop inside the building he cocks the gun again. Thus, he is holding up Sever without any shells in the gun.

Continuity: In the long shot of the sniper falling down onto the car, you can see that there is nobody standing next to it. Yet when the crash sends the tyre flying, suddenly some policeman is right beside the car getting hit.