Monty Python's Flying Circus (1969)

Blood, Devastation, Death, War and Horror - S3-E4

Visible crew/equipment: When the Merchant Banker sends Mr. Ford through the trap door, you can see a crew member waiting to catch him below the stage. (00:06:50)

Sex and Violence - S1-E1

Factual error: When the allies are testing their joke on the private in the field, just before he starts laughing at it, a bright red car drives past behind him. You can see it in a break in the trees. This sketch is set in WW2, and the car is obviously not from that era.

Intermission - S1-E13

Visible crew/equipment: Just after Florence Nightingale gets knocked out, a crew member can be seen behind Michael Palin for a short time.

Scott of the Antarctic - S2-E10

Revealing mistake: In the last shot, the familiar 16 tons weight is broken at the top, showing that it is in fact not a solid weight, but a hollow box.