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.
Other mistake: When Marcus, Kyle and Star are at the petrol station, a flying HK and the giant Harvester robot are able to appear just outside without making any kind of sound. In every other scene of the Harvester and the HKs however, they both make an incredible amount of noise.
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: 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 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 the Saab 900 car is destroyed by the Harvester, it already has momentum and you can see whats left of the car thrown in an arc into the air. When it lands however, it simply drops vertically, which it wouldn't do, it should have fallen in a decreasing arc.
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 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: 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.
Continuity mistake: When Kyle and Star are fleeing from the gas station, being chased by the motorcycle Terminator, the wrecking ball on the truck is swinging wildly. In the next shot it's firmly hooked to the left side of the truck and then in the next shot Kyle is told to release the ball and it's loose again.