Continuity mistake: When Denzel Washington is injected with the tracking device,it is injected behind his ear. But later, when he looks at his cop friend and says something to the effect of "Get my gun", the band-aid is on the side of his neck.
Continuity mistake: Right after Sid comes to life he cuts his finger off. When you see the actual cut, it is just the tip of the finger, but when you see his hand afterwards, it is more than half the finger that is missing.
Continuity mistake: When Parker is chasing Sid through the studio building, there's a scene where ricochets are sparking all around Sid even though the previous shot shows Parker pinned down by Sid's gunfire.
Continuity mistake: During the count down of the bomb, the clock would have reached zero several times. You hear clicks from the clock, and there are far more, than there are seconds left.
Continuity mistake: During the final fight, the holes in Sid's back keep changing position and number.
Continuity mistake: When the burning tanker truck is blocking the road, you see cars moving away behind it. But since it blocks the road completely there couldn't be cars on the other side.
Continuity mistake: In the wrestling arena scene, Russell Crowe has his hand blown off by a shotgun blast. He makes his way into the ring, then shortly afterwards jumps out, using both hands to steady himself on the wall. When he comes out of the stairwell to the train platform his hand is missing again.
Chosen answer: 24.