Papa Smurf is walking with Peewit in the Smurf Village wearing white trousers instead of red. When Clumsy accidentally hits Peewit, Papa Smurf's trousers are back to the normal red.
The Smurfs are shown running past the captain of the guard after he was knocked down by Johan, but after he exclaimed that he saw "blue rats", the Smurfs are shown running past him again.
At the end of the episode, when Peewit throws the red marble to stop the baron from stealing the gold, the gold turns into gray lead, in the next scene the king complains that all the gold is now lead and completely worthless. A gold crown can be seen on top of the pile. Also, the golden goblet that earlier had been on Peewit's head is nowhere to be seen.
Johan and Peewit stopped a wagon carrying cakes heading to Bourgeoile Castle. However, many of the cakes are made from chocolate which was unknown in Europe until it was imported from the Americas in the 16th century. Also, food made from chocolate (e.g. cakes) existed much later. The background of the Smurf cartoon series is the late Middle Ages (circa 14th-15th centuries), early for the appearance of chocolate and food made from it in Europe.
Papa Smurf told Johan at night that Baron Maltrochu left in the morning to Bourgeoile Castle for his wedding with a dozen men. Actually, in a previous scene that took place during the morning, Maltrochu left with only three men, not a dozen as Papa Smurf said.