King Ottokar's Sceptre: Part 1 - S2-E4
Other mistake: Tintin walks into Hector's apartment to give him his briefcase. An animation error occurs regarding his magnifying glass in the shot where Hector says "Just leave the mail on the table if you please." For the first few frames of shot, the circle around the edges of the magnifying glass is colored yellow. Then as he says the line, the edge of the magnifying glass suddenly flickers to black during the shot. (00:01:55)
King Ottokar's Sceptre: Part 1 - S2-E4
Other mistake: The menu at the Syldavian Restaurant Tintin is handed doesn't have any writing on it. (00:05:55)
King Ottokar's Sceptre: Part 1 - S2-E4
Other mistake: When Tintin storms into Hector's apartment, the door handle is never seen turning when he enters. (00:11:45)
Chosen answer: It is a pill that makes alcohol taste disgusting.