Plot hole: When Grams is summoned for Chris's wiccaning, she reminds Piper of "the talk" they had when she was a teenager, about how important and special being a witch was to Grams and how it would be to the girls someday. But in the first episode, the girls have no inkling they are witches, and when they find out it's passed through the maternal line, they wonder if Patty or Grams was a witch - suggesting that they aren't sure or have no memories of them as witches. I know there was some memory altering at certain points, but why would Grams have a conversation specifically about how great it is to be a witch and then erase that?
Continuity mistake: When Leo hugs Wyatt near the end of the episode, the way the pair hold onto each other changes. (00:38:15)
Chosen answer: Her agent/manager negotiated a special billing as part of her contract. It distinguishes her from the rest of the cast, probably when she became a producer on the show.
JC Fernandez