The Secret of the Unicorn: Part 2 - S1-E4
Other mistake: All the shots fired at Barnaby went into the wall. The bullet holes are even there to prove it. This shows us he was never shot. Yet for some reason, he acts as if he was shot. (00:32:15)
The Secret of the Unicorn: Part 2 - S1-E4
Other mistake: Tintin is in the treasure room whilst the Bird brothers are looking for him. After the brother with the gun shoots the knight armour, Tintin is crawling around the room far behind them, and pops his head up where he can see them. About 2-3 seconds later, he is then shown as a mirror reflection the brothers are tricked into thinking is real, nowhere near his previous spot. 4 seconds after that, Tintin is hiding behind a cupboard at the other end of the room, that the brothers just quickly run by. (00:37:20)
The Secret of the Unicorn: Part 2 - S1-E4
Other mistake: The inside of Snowy's mouth is white when Tintin says "Captain, I'm fine". (00:40:20)
Chosen answer: It is a pill that makes alcohol taste disgusting.