In "A Myna Problem," a myna is a prominent character in this episode. However, mynas are only found in Southeast Asia, not Europe (which is the setting of the Smurfs cartoon series).
In "The Horn of Plenty," chipmunks and other animals appeared in front of Nat. However, chipmunks are found in either North America or Asia, not Europe (which is the setting of the Smurfs cartoon series). They should have not appeared at all.
In "The Horn of Plenty," due to the food shortage, the Smurfs were forced to eat seeds from a corn ear. However, corn (a cereal grass originally domesticated in Central America) was unknown in Europe and will not be cultivated there until the early 16th century. The background of the Smurf cartoon series is the late Middle Ages (circa 14th-15th century), early for the knowledge and cultivation of corn in Europe.
In "The Horn of Plenty," Brainy is leaning at a corn field which quickly collapsed and he fell on it because of Mother Nature's use of a bad wand that caused a fog that killed every edible plant in the forest. However, corn was unknown in Europe until it was imported from the Americas in the 16th century. The background of the Smurf cartoon series is the late Middle Ages (circa 14th-15th century), early for the appearance of corn in Europe.