The Crab with the Golden Claws: Part 1 - S1-E1
Continuity mistake: Tintin is locked in a room tied up to two pipes. There is rope around his torso and ankles which is connected to the pipes above and even his arms are tied up, connected to the pipes behind him. Allan then enters the room and the rope that was connecting his arms to the pipe is now nowhere in sight. It is partially visible for a few frames, but then vanishes for the rest of the shot. Then when the shot cuts to Tintin, there is suddenly rope wrapped all around the pipe behind him. (00:12:35)