Revealing: When the black Knight is sitting on the ground with no arms or legs, the ground right next to him bends down, indicating his legs were buried.

Revealing: When the Black Knight kills the other knight by throwing a sword through his head, you can see that the blood is coming from the sword, not the wound itself. Likely the actor had a blood tube in his hand, and let the blood run down the sword and splatter onto his face.

Other: It's revealed that the Knights who say Ni can't say "it" (at least, after they become the Knights Who Say... that other thing), but they still say "it," most notably when they're telling Arthur to place the second shrubbery next to the first one - "When you have found another shrubbery, you must place IT here, beside this shrubbery..." Submitted by Xofer

Visible crew/equipment: In the scene when Sir Robin meets the three headed man, you can just about see the boom mic above them. It is about an inch below the top of the screen.