While escaping from Gargamel and Azrael at the beginning of the episode, Handy and Clumsy entered a hole that belongs to a gopher. However, gophers are native to North and Central America, not Europe (which is the background of the Smurfs cartoon series), so that gopher should have not appeared at all.
Handy is shown putting the finishing touches of a mechanical scarecrow he made for Farmer which has a pumpkin head and a carrot nose. However, pumpkins were unknown in Europe until they were imported from the Americas in the 17th century. The use of pumpkins for decorative purposes (e.g. carving images from them) came latter on. The background of the Smurf cartoon series is the late Middle Ages (circa 14th-15th century), early for the appearance of pumpkins and their decorative uses in Europe.
Handy's mechanical scarecrow is shown mowing over the stalks in Farmer's cornfield because Clumsy foolishly removed the rock that kept it from sliding down a hill. 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.
In the beginning of the episode, Gargamel is shown putting Clumsy into a hero sandwich containing tomatoes so as to eat him alive. However, tomatoes were unknown in Europe until they were 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 tomatoes in Europe.