The Crab with the Golden Claws: Part 1 - S1-E1
Revealing mistake: After Snowy tackles the man, the man throws him onto the ground and then says "I'll tend to you later, mutt", then turns his head to Tintin and says "But first I'm gonna take care of you." Just as the shot ends, Tintin's mouth vanishes from shot for a brief frame. (00:06:15)
The Case of the Missing - S1-E1
Revealing mistake: WPC Softly leans on a model building in Rammel's office, causing it to collapse by stages. The wire that is being pulled to make the model collapse can be seen to the right of the model. (00:21:00)