Revealing mistake: When Tintin and Snowy arrive in Chicago on the train, whilst Tintin says "Here we are Snowy. Chicago", his fingers pass through the window frame of the train. (00:02:20)
Continuity mistake: As Tintin and Snowy are walking out of the train station, there are two taxis parked outside. When Tintin is offered a ride, there is only one taxi, and the other taxi has been replaced by a purple car. (00:02:25)
Revealing mistake: When Tintin is getting into the taxicab after leaving the train station, the cars driving on the road in the background are the exact same purple car design duplicated over and over. (00:02:30)
Revealing mistake: When the driver covers the windows in the taxicab, in the shot where he says "Too bad you won't get to appreciate the view", the cover shown between the back seat and the front seat has visibly not been fully drawn in yet, and an unfilled gap can be seen in the cover. (00:03:05)
Audio problem: When Tintin checks into his hotel room, he thanks the bellboy, but his lips do not move. (00:05:40)
Continuity mistake: When Tintin phones the operator to connect him to the police, she is holding a green wire. Then when the Mafia member takes it off her the wire is now blue. (00:07:05)
Continuity mistake: When Tintin follows the mob member from the diner to the building, the scene cuts to an exterior shot. A hot dog stand is shown outside the building, with a vendor standing beside it, but in the next shot, the vendor is suddenly standing behind it. (00:16:40)
Revealing mistake: When Tintin is writing his news report on the mafia, the writing does not appear when typed, but instead appears one row at a time. Also, when he removes the paper from the typewriter, several rows of writing have suddenly appeared. (00:20:50)
Chosen answer: It is a pill that makes alcohol taste disgusting.