Revealing mistake: As Connie approaches the graveyard the sky in the background is obviously a painted backdrop, as there is a visible seam.
Revealing mistake: In the window there are already broken areas where the glass gets broken when Captain hits it. On the bottom pane the grill on the top, bottom and right have a crack before the Captain even hits it. (00:19:00)
Revealing mistake: Many of the "frozen" Union soldiers can be seen blinking, breathing and wavering in place amidst their regiment. (00:07:30)
The Jungle - S3-E12
Revealing mistake: The "mannequin" dressed as a warrior in the costume shop window is a live actor; watch closely and you can see his eyes widen ever so slightly. (00:14:55)
Revealing mistake: Stock footage used here is far too obviously borrowed from several old movies. While the episode is set in the 60s, people's clothing and all the cars are noticeably many years out of date. (00:03:05)
Hocus-Pocus and Frisby - S3-E30
Revealing mistake: Make-up for the space aliens was apparently changed after the closing scene in the store was shot and before any footage of the aliens' "true appearance" was actually taken. This resulted in Frisby, who is now telling the truth and finding no one to believe him, saying that the aliens had a single eye in their foreheads, when in fact, the aliens each had two eyes, in the traditional location. (00:24:00)
Revealing mistake: At the end, though Williams is shot multiple times (by several rifles, no less), there's not a drop of blood on him and no holes in his clothes. Also, his "corpse" is visibly breathing. He's clearly meant to be dead, so the fact that he's an alien with healing powers does not explain why he's still breathing - or why the bullets left no holes or blood on his clothes. (00:22:30)