The Castafiore Emerald: Part 1 - S3-E7
Revealing mistake: When Castafiore is showing everyone the Castafiore emerald, after she says "He named it in my honour", the shot cuts to a close-up of her hand, saying "The Castafiore Emerald." At the start of the shot, she has two rings on two fingers, then she turns her hand and the two rings vanish from her fingers entirely. (00:09:00)
The Castafiore Emerald: Part 1 - S3-E7
Revealing mistake: When Castafiore locks her jewels in the drawer, she places the key inside the lock, but the key visibly surpasses the edge of the lock. (00:10:00)
Chosen answer: If Hector was seriously intent on removing King Ottokar's scepter from the glass cage holding it and launching it through the window with the camera, then Hector would have been forced to knock out the two guards so they would not have interfered with Hector's plan as soon as he removed the scepter from the glass. As for Hector, himself, was explained when Tintin was explaining how Hector stole the scepter. Tintin placed a twig inside the camera and it launched out of the camera. Hector would have placed the scepter inside of the camera, and would have been knocked unconscious due to the spring effect created when the scepter had been launched.
Casual Person