Continuity mistake: Whilst examining the wrapper with "Karaboudjan" written on it, the "K" is a centimeter away from the letter "A" and all the other letters are about a fifth of a centimeter away from the letters. Tintin then places a magnifying glass above the word "Karaboudjan". After doing this, the "K" that was a centimeter away from the "A" is now a fifth of a centimeter away from the "A", but none of the other letters seem to have changed distances.
Revealing mistake: After Haddock snaps the door to the window, the big guy enters the room pointing a gun at Haddock. The shot then cuts to Haddock with fruit all over the place. Look to the left of screen and you'll an apple laid on top of another apple completely unnaturally.
Continuity mistake: As Haddock cleans his teeth, the news on the radio states that Castafiore was arrested so Haddock spits out his gargling water. Some of the water and toothpaste goes over his beard. But when he runs into Tintin's room, his beard is as dry as a bone, with no toothpaste in sight.
Continuity mistake: When the episode starts, Tintin rides into Marlinspike Hall on his motorbike. From a side angle of the bike after it has driven inside, the brace thing around the bike's wheels is black. After Haddock says "Ahoy, Tintin", the brace thing has become green.
Revealing mistake: Haddock becomes exhausted and sits down. Tintin points out he'll freeze. Watch the two horizontal strips along the middle of his jacket. They are yellow for a few frames, then they go to blue for a few frames. Then if you look super carefully, you'll see that the two straps vanish from shot for a quick sneaky frame. Then they reappear.