In various episode of "Sabrina", Hilda mentions being around 615 years old.  However, that is impossible, because in the episode "Dante's Inferno," she claims that when a boy first gave her a star, three wise men followed her around.  Through this reference, we learn that Hilda Spellman is at least 2,000 years old.

        In the episode "To Tell a Mortal," Hilda is supposed to have a bat fly out of her mouth, but you can tell its a bird. (Also, when she spits out a bass [fish], you can tell she had it in her hand before.)

        In "Witch Trash", for revenge Hilda and Zelda's hillbilly cousins messed up the labtop.  They still use it, so can we assume that Zelda fixed it, or did she still have a warranty on it? And can't Racine just zap her husband a job?

        In "Mom vs. Magic," the Quizmaster says that Sabrina is forbidden to have any contact with her mother until she turns 18, but in "Meeting Dad's Girlfriend," Sabrina A. Calls her on the phone and B. Actually spies on her via the Magic Book.

        In "Sweet and Sour Victory," Sabrina freezes time to help Gordie with his math test.  But in the following season, in the episode "Sabrina Gets Her License," Sabrina is unable to freeze time or speed up time.

        In "Pancake Madness," Sabrina learns that she is forbidden to eat any pancakes (love the "Pancakes" dance sequence with Mrs. Quick!) but in the "Pilot", she is served them for breakfast.