Factual error: Considering how the sisters and Cole every now and then - especially during seasons 3-5 - find themselves in some churchyard or cemetery, it should be noted that there are no such places in San Francisco! Except for the original one at an old nunnery, from before the city was founded, and the Presidio Military Churchyard, all graves were moved in the first half of the 20th Century to the cemeteries at Colma, a few miles south of SF. This was done due to the sanitary risks in case of earthquakes, and the lack of space for churchyards downtown.
Factual error: Throughout season 8 the members of the Triad wore a pentagrams on their gowns that would alternate from the point being up and point being down. They should only be wearing a pentagram with the point facing down. Pentagrams with the point facing up is the symbol for practitioners of white (good) magic while those who practice black (evil) magic is symbolized by the point facing down.
Factual error: Numerous times in the establishing shots of San Francisco, the Embarcadero Freeway is visible. While the bridge did run along the San Francisco Bay, it was demolished in 1991 - seven years before the series even started.
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