The Calculus Affair: Part 2 - S1-E13
Continuity mistake: As Tintin, Haddock and Snowy are running whilst being shot at, Snowy is holding Calculus's umbrella with his teeth. The handle is facing the right as this happens. However, when they are shown in the helicopter, Snowy is suddenly seen holding the umbrella with the handle facing the left. (00:28:25)