Show Ghouls - S7-E15
Plot hole: When Leo tells Piper that he believes he found the demon Sargon in the Book of Shadows (which may be the demon Count Roget made a faustian deal with), Piper looks at it and says that they vanquished this demon five years ago. Which would've meant they vanquished the demon with Prue. When in fact the only demon that happened with was Zahn in season 6 episode 6, "Soul Survivor," and they did that with Paige.
Show Ghouls - S7-E15
Continuity mistake: When Phoebe is on the phone with Elise about the Cosmo interview, she jumps between shots from leaning over the kitchen table to sitting straight up. (00:05:45)
Answer: "Hush, Hush, Hush" Paula Cole.