Continuity mistake: Piper says she wants to go to Paris by plane not by orbing, but in the episode "From Fear to Eternity" flying was Piper's greatest fear.
Continuity mistake: When Prue, Phoebe, and Leo enter the kitchen to find Piper covered in watermelon, the amount of fruit on Piper changes in the next shot. Her hands also change from being supine to prone. (00:19:00)
Continuity mistake: When Piper accidentally blows up the teapot, she has her hands up by her chest, in Prue's, but in the next shot her arms are down by her sides. (00:19:55)
Continuity mistake: When Piper accidentally destroys the clock at the passport agency, she freezes in fear with her hands near her face. In the next shot, her left hand is suddenly back by her ponytail. (00:13:40)
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