Revealing mistake: When Connor and Cameron are trying to save Derek Reese from the police truck, Cameron walks on the Jeep's hood to jump onto the police truck. During her walk, we can see that it isn't Cameron but a stunt double. She doesn't look like Cameron and is a bit taller.
Revealing mistake: Some of the security cameras in the Weaver's household are in some rather odd locations. We see a camera's point of view of Savannah looking up through the glass table that she's doing her homework on, and a camera's point of view of Savannah hiding behind the TV. Besides the obvious need for John Henry to keep an eye on her, what is the need for these cameras? And where are they placed? Later on in the episode, when John Henry is talking to James Ellison about why he stopped looking for Sarah Connor, pretty much all of the cameras on the wall next to them are recycled shots from the actual show and couldn't possibly be from physical cameras due to their awkward angles.
Revealing mistake: In Cameron's Story, in the scene with her and Derek, Derek's phone rings. When he looks at the screen it shows a telephone number and the words "EDIT" and "BACK" in the bottom corners. The phone is not in fact ringing at all. Derek is merely looking at the details of a contact saved on the phone.
Revealing mistake: Look at Summer Glau's face when she jumps off the Jeep onto the black van and punches the windshield to throw the driver out - it isn't Summer Glau. It's her stunt double, Sonja Munsterman. It isn't even Lena Headey driving the Jeep or Thomas Dekker sitting in the back.
Revealing mistake: "Season 2, Episode 20: To the Lighthouse." When Cameron is firing back at the man on the passenger side of the van coming at her, the man drops the gun in his lap when Cameron shoots him. The very next shot shows the gun tumbling around on the road on the opposite side of where he was shooting.
Revealing mistake: Ep. "Samson and Delilah" - As Cameron flips over the Jeep Cherokee, the smoke coming from the bottom of it is from the cannon used to flip it, the cannon in later shots then disappears, more notably when the camera goes above the Jeep with Sarah crawling out.