Continuity mistake: In the scene where Blair escapes with Marcus and Barnes launches an explosive into the tunnel, Marcus hops onto Blair to save her from the scorching flames. After the fire, Marcus' coat would have been burnt to a crisp, his hair singed off and the skin on his back fried. More evidence pointing to this was that his coat was merely one previously worn by a Resistance fighter, not special in any way, and he has regular skin and hair.
Continuity mistake: John Connor, whilst battling the T-800, fires a shot into a wall to create an opening. Star jumps through the hole to the left, Kyle jumps to the right, and John jumps through the centre, yet in the next shot Kyle has landed in the centre and John has landed on the right.
Continuity mistake: When Marcus was freed by Blair and they are trying to escape through the shaft, Barnes shoots a rocket at them. Marcus lies on top of Blair as the fire goes through the shaft, but you can see that Blair's hair is sticking out from under Marcus. When they get up, Blair's hair is not burnt at all.
Continuity mistake: This is right after Conner jumps down to the lower level to get to the grenade launcher and hurts his shoulder. He is crawling away from the T-800 and the shot is from right behind Conner's head. The T-800 is practically right on top of John, but when he shoots the oven and the molten steel lands on the T-800, the shot shows John like 30 feet away.
Continuity mistake: When Marcus is driving the big tow truck down the highway, he smashes into the back of a red VW Jetta with custom chrome wheels that is parked on the right side of the road. A few shots later, the same car is shown again, now on the left side of the road, and is hit again. That's fair enough, as the truck seemed to reverse direction when the first bike crashed into the bus. But seconds after the second hit, this car is again on the RIGHT side of the road, and is struck a third time (this is actually the first hit, shown now from a different angle).
Revealing mistake: After Marcus rips out his chip implant, he picks up a steel stool and throws it through the screen. The stool stops in midair as soon as it breaks the screen, which is a mistake in itself. The stool does so because there are wires connected to the stool, at least one of which is visible: a microfilament wire from which the stool is suspended. It is attached to the the stool at the pole between the upper and lower plates. The displays on the other computer monitors in the background appear to have been meant to help disguise this, but one line in particular moves in perfect sync with the stool. Also, the wire snaps taut, then wiggles with slack, whereas the lines on the monitors remain completely straight at all times. A previous correction claims that no wire is visible, but that is completely erroneous.
Continuity mistake: When the Harvester destroys the Saab sedan that is fleeing the fuel station, the car's chassis is shown sailing through the air, stripped of its interior and drivetrain, throwing random sparks, but not on fire in any way because there's really nothing left that would burn. But moments later, it is completely engulfed in flames as it crashes through the awning over the gas pumps.
Other mistake: A spelling mistake in the credits lists Diego Lopez as a "soilder" instead of the intended soldier.
Continuity mistake: When the Resistance has a Hydrobot on the table testing out the jamming shut down signal, they have recycled footage when editing the film together. When they strap the Hydrobot down to the table, the shot changes to a close frontal shot of the Hydrobot and the straps have gone. The shot then pans out to a more distant perspective and the straps re-appear. The shot goes close up and the straps vanish again
Continuity mistake: When Marcus and Kyle are being chased by Moto-Terminators, Kyle kicks the oil barrel off the truck to hit one of the Moto-Terminators. Later, as Kyle reaches rearward to release the tow hook, the barrel is shown still on the truck, standing as it was before Kyle kicked it off.
Continuity mistake: You can see 5 point belt harnesses on Kyle and Marcus when they are in the Jeep. Yet you never see them put them on, or take them off. Kyle is pushed out of the driver's seat once they stop.
Continuity mistake: This is near the end of the tow truck chase scene. Just when the truck hits the railing and Kyle and Star are thrown from the truck, Kyle is caught in the right hand, Star is caught in the left hand. But when the shot is coming from inside the transporter, Kyle is dropped from the left hand and Star is dropped from the right hand.