Corrected entry: In the first scene when they show the Vestal Virgins lying around, the girl on the right of the first pair can be seen quickly glancing at the camera.
Corrected entry: A running joke in the Roman Empire segment is the use of "V" in the place of "U" on all signs. However, on the "Annual Orgy" banner, there are two "U"s instead of "V"s.
Correction: Probably done deliberately as an inside joke.
Corrected entry: During the Inquisition song, right before Mel Brooks says "Skit skat Vodely dat Boopadyday" or something like that, the shadow of a pole is visible on the steps to the right.
Correction: You do see a shadow, but it could be anything from the dungeon. it could be from the railing, one of the chains seen hanging about, or one of the torture devices.
Corrected entry: The shot with the nuns rising from the water in the Spanish Inquisition segment is obviously a reverse shot of the girls lowering into the water, but not much care seemed to go into disguising that fact: the sparks fly back to the sparklers on their heads, and so does the smoke that comes from them.
Correction: This is a deliberate directorial decision. The scene is a parody of the water ballet scenes done in the golden age of Hollywood, where such primitive special effects techniques were often used. This does not qualify as a mistake.
Correction: She could have been looking at a fellow virgin just off camera. There is no proof that she is looking at the camera.