Factual error: Tintin says they only have one bullet left. That bullet is in the magazine,and since it is a semi automatic, there should also be one in the chamber, meaning they would have two bullets. Even if they only had that paticular bullet, he doesn't cock the gun, meaning the chamber would be empty and therefore wouldn't fire.
Factual error: Towards the end when the smugglers are trying to takeoff from the airport with the float coming at them, Marcel (the lead smuggler) tells Tipa (the fat smuggler) to pull up because they're about to hit the float. Tipa quickly pulls back on the flight controls to takeoff. The scene switches to an outside shot of the plane's wing where the "flap" moves to the down position, but pulling back on the controls manipulates the "elevator" (on the tail) which would cause it to pivot upward. The flaps are controlled separately. (01:20:40)
Factual error: The 'Mayor' says he's a Turtle, but he's actually a Tortoise. Turtles have paddle type limbs for swimming, not reptile like paws as depicted in the movie.
Factual error: The scene showing Paris at night displays heavy traffic and bright car headlights over the distance. Both were not possible to be seen at time the story occurs, circa 1920's.
Factual error: When Benjamin's brother arrives in his car with the bear's fish, he opens the trunk with a remote key. The car is a Mercedes 240 Diesel (to be more precise, a W123 series), built from 1975 to 1986. Mercedes first introduced a remote key system to the W140 series at the beginning of the nineties. (01:35:45)