Tintin in Tibet: Part 2 - S2-E7
Revealing mistake: After the "previously" clip, Tintin, Haddock, Snowy and Tharkey continue their walk. In the second shot, the four walk over a hill. The first footstep on the edge of the hill is incorrectly drawn and looks unrealistic. (00:24:45)
Chosen answer: It is a pill that makes alcohol taste disgusting.