Continuity mistake: When Spartan and Huxley arrive at the cryogenics place to battle Phoenix and what remains of his gang, Phoenix sees them on the monitor walking into the building and you see Spartan on the left and Huxley on the right. The camera angle changes to an inside view and Spartan is now on the right. (01:38:35)
Continuity mistake: When Spartan switches seats with Huxley in the police car, the outside shot shows him get into the back seat. When the shot switches to Huxley in the driver's seat, we can see the back and Spartan isn't seen anywhere in the car. (00:42:40)
Continuity mistake: When John Spartan is frozen in the cryochamber, at the beginning of the movie, if you watch during the credits - while the time is going by the small circular monitor that is on his chest and head, it changes from the left side to the right side of his chest and head in almost every shot. (00:10:10)
Continuity mistake: During the final fight scene, Spartan grabs Phoenix and they land on top of the ice block and roll off in front of a few metal jugs. The camera angle changes to a close up and the jugs are not there anymore as you see Spartan punching Phoenix. (01:46:35)
Continuity mistake: During the glass floor shootout at the museum Spartan shoots a light that falls through the glass. Right after Spartan shoots the light it goes dark but the close up of the light falling and hitting the floor shows the light to be still lit. (00:49:05)
Continuity mistake: When Phoenix first gets out he makes his way to a computer and the police come to arrest him. Phoenix takes one of the policeman and pushes his head through the side glass pane and walks away to fight the other officers, but when Phoenix goes back over to the computer the glass is not broken. (00:26:50 - 00:27:40)
Continuity mistake: When Spartan and Huxley go to Raymond Cockto's place, Spartan shoots all of the monitors with a silver gun, yet when Spartan points the gun at Cockto's head, which we see on the surviving monitor, it's a black gun. (01:18:25)
Continuity mistake: When the Cryo-Prison worker opens the cabinet that holds the cylinders that contain the blue "freezing balls" to freeze Spartan's slush, the slot on the center left is empty. When the shot changes to the worker pulling the cylinder out, the slot to the lower left is now the empty one. (00:09:45)
Answer: I'm assuming you're referring to when Simon says "Damn, I'm possessed!" He was hacking the machine when he said it, perhaps he'd corrupted the program or shut off the microphone as a side effect?
Grumpy Scot