Other mistake: After Piper tells Phoebe to get to know Dex well and fast because it may be the one sign Phoebe can't ignore, Piper ends the family meeting. In the following overhead shot as Piper walks out we can see her reflection in the wall mirror and it shows her long dark brown hair, but the problem is the reflection should be showing the "Jenny Bennett" golden blonde hair instead. (00:05:05)
Hulkus Pocus - S8-E9
Other mistake: When Piper is explaining to Phoebe that they don't have enough time to save Billie, she lists all the things they need to do ending with "fix us and then fix Billie..." This doesn't make any sense, since when she's saying it there's nothing wrong with them to fix. It's only after she says this that they come up with the plan to infect themselves. (00:29:54)
Other mistake: When The Angel of Death comes to Leo in the car Leo asks him "can I at least see my son again?" which is an odd way to ask that question given that he has two sons.
Repo Manor - S8-E13
Other mistake: When Piper blows up the dollhouse, killing Pilar, Phoenix and Patra, you can hear the sound effect of telekinesis, despite Piper's power being molecular combustion.
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