A Thing About Machines - S2-E4
Revealing mistake: After Bartlett Finchley escapes from the menacing electric razor, his car confronts him outside. When Finchley's car chases after him, there's nothing attached to the Lagonda, but when the car slams through the wood fence and into the wall of boxes, there's a full grille guard mounted to its front. Then the grille guard promptly vanishes. (00:20:30)
Stopover in a Quiet Town - S5-E30
Visible crew/equipment: After Bob and Millie realise the tree and the grass aren't real, when they head towards the town Bob calls out, "Hey! Hey, anybody here?" Then Millie adds, "Somebody," and the shadow of the boom pole/mic moves across the bottom of the screen. (00:14:55)
The 7th is Made Up of Phantoms - S5-E10
Factual error: Numerous references are made regarding George Custer being a general at the Battle of the Little Bighorn when, in fact, he was a lieutenant colonel.
Answer: #4: That he did personally murder at least 14 (Jews). The last word I couldn't quite hear because of the screams, but I hear an "-oz" sound at the end, so it's an educated guess. #5: That he did sign and put into effect specific orders calling for the gassing and cremating of one million human beings.
Bishop73