Destination Moon: Part 2 - S3-E10
Deliberate mistake: The shot of the plane landing in Syldavia at the start of the episode, after the recap of part one, is merely the exact same shot of the plane landing in Syldavia at the start of the previous episode. Note the vehicles on the ground are completely identical and the plane, as well as its movements are also identical. (00:25:00)
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