"The Enchanted Quill" contradicts an early season episode ("The Winged Wizard") where Gargamel was forced to tear up his wizard school cap as part of a spell, indicating that he graduated from wizard school. In "The Enchanted Quill," the wizard school dean and Gargamel himself both say that the latter never graduated.
In "The Enchanted Quill," Gargamel unexpectedly confronted skunks while catching the Smurfs, but they are found only in the Americas, not Europe (which is the setting of the cartoon series).
Sassette foolishly takes Mother Nature's wand from Nat to change the odor of a passing female skunk. However, skunks are native to the Americas, not Europe (which is the location of the cartoon series).