Revealing mistake: When the children are possessed by the 456, they're supposed to be frozen and stare blankly ahead. But during the second possession, as the camera is panning across a school playground, a boy on the far right is looking directly at it. As it moves closer to him, he swivels his eyes back to where they're supposed to be. (00:16:30)
Revealing mistake: When Carter and Jo almost crash into the reflective smart dust wall on the road, Carter puts his hand up and waves it, to see his mirror image doing the same. Carter's mirror's hand movements are out of sync, which reveals that the "mirrors" are the actors, and the "real people" are doubles.
Revealing mistake: In an early episode Jack introduces Tracey to all the TGS writers, but giving mini bios and facts about them in rapid Succession. Seconds later we go to a flashback of Jack's assistant holding up pictures of random people as Jack names them. The problem though is you can see that it's the same picture being used every time.
Revealing mistake: After Round Alpha-1 concludes in the Inner City Academic Amathalon, Vinnie complains that he should have studied, and his head falls to the table. However, for about 1 frame before his head falls to the table and Rocket grabs his ear, the shadow of his head can be seen on the table while his head stays upright. (00:09:20)
Revealing mistake: After Betty leaves Jodie the voicemail, when Betty looks at Henry's Facebook page with the intention of unfriending him, she moves the cursor to the "remove friend" tab. Then in Betty's closeup we see that tab's reflections on both lenses of her eyeglasses, but the problem is the reflections are not backwards. (00:33:35)