Sabrina the Teenage Witch (TV series)/WMG

The Pilot is simply Non-Canon.
So much ended up being retconned in the actual show:
 * Probably the most infamous, Sabrina was told that she could not see her mother until she obtains her Witches' license. For the rest of the series, it is made clear Sabrina cannot see her mother ever again.
 * This was reffered to repeatedly up until the point when she actually gets her witches license. And before that I belive they'd even specified it as being a time limit of a couple years so the witches license thing was already a retcon.
 * Sabrina was told a witch only comes into her powers (and is told about magic) when she is sixteen. Child-witches can be seen throughout the series (such as, but not limited to, Cousin Amanda)
 * Sabrina's father can talk to her through a book, and tells her he will always be there for here (in the book) if she needs him. This idea is never used throughout the rest of the series, even though her father does appear in later episodes (though in person).
 * The spin-off books, ironically, actually used this idea more often, though they were a different continuity than the show.
 * To a lesser extent, Hilda making a catty remark about Sabrina's mother, since there does not seem to be any animosity between them for the rest of the series, though to be fair, it is not like they really interacted.

The entire show is a giant metaphor for the Wiccan rule of three.
The practicality of having magic in this show and using it for personal use is wildly marred by all the problems it causes. Although most of the time it is put down to Sabrina being an inexperienced witch, even her Aunts are tortured with various magical problems in nearly every episode (knocked out by magic poppies, sealed in their own home, various misfortunes because of chain letters). The Wiccan rule of three is that anything you give back comes back times 3. It seems in this show the only appropriate way to use magic is only when strictly necessary -think Tara from Buffy the Vampire Slayer-, or face horribly inconvenient consequences. Goodness knows what type of hell she'd go through if she used magic properly like we all would (improving our appearance, improving grades, zapping ourselves everywhere instead of travelling).
 * This is partially Jossed by the fact that Sabrina still suffers consequences even when she was only trying to help people. Using her powers for small, hedonistic things seem to be the only things that do not cause Sabrina problems.