Continuity mistake: Near the end of the film, Adam and his clone make a jump for the helicopter to escape the explosion. In one scene, you'll see Sport Jacket Adam holding the ladder to the helicopter with Leather Jacket Adam holding onto the legs of the first Adam. After a cutaway scene, you'll see these two have switched places (Leather jacket on ladder, Sport jacket on bottom). The next time you see them, they're switched back in the correct order.
Continuity mistake: Towards the end of the movie, in the scenes involving the dying Drucker (Tony Goldwyn) and his half-formed clone, blood on the dying Drucker keeps disappearing and reappearing. In one scene he is bleeding out his mouth and down the front of his throat. The camera cuts away and when it comes back his throat is clean. Yet in the next scene his throat is bloody again.
Continuity mistake: When Drucker jumps from the roof onto the glass at the end(to avoid the rotors of the Whisper Craft), the establishing shot shows him on the last panel of glass next to the wall. However when you see Drucker fall from the inside shot, he falls from the middle of the glass roof and no wall is seen anywhere near him.
Continuity mistake: When Schwarzenegger returns to his company and removes the photo of him and his family from his locker he then looks in the mirror at his shaving cut, in doing so lifting his cheek right up to see the cut which is obviously under his chin. In all the other scenes however, the cut is clearly visible without having to pull or distort the face.
Continuity mistake: When Adam is in the police detention room, he props a chair under the doorknob to keep anyone from entering. The chair is propped with the seat up, but when the police break in and the chair flys away from the door, you can see that it had been positioned with the seat down.
Continuity mistake: Near the end of the movie there's a scene where the lead antagonist meets his clone, the antagonist's sweater has a hole in it from where he was shot. The clone needs the antagonist's clothes and takes them from him, but the hole from the sweater is missing. In another scene, the hole is present.
Continuity mistake: In the final shoot out on the roof there is a quick shot of Arnold firing a gun wearing the grey security outfit he stole from the guard earlier in the film. The only problem is at the time one Arnold is wearing his leather flight jacket and the other is still dressed in the sport coat outfit he wore to his daughter's school. This is obviously a shot from an earlier scene they used again later.
Continuity mistake: When Adam enters the building with the girl's thumb, he gives the cooler to the security guard who begins to remove the tape, then the shot cuts to a view of Adam across the desk and the tape is back up, then when it goes back to the POV of Adam looking at the guard, the tape is back up.
Continuity mistake: When Talia is first killed, while in the Cadillac, the passenger door is blown off. When Adam drives through the water there's an inside shot of him and you can tell the door is back on for the scene. After going down the stairs there's the same inside the car shot of Adam and you can see the door is missing.