From Fear to Eternity - S1-E13
Plot hole: Prue finds an entry in the book of shadows about the fear demon written by her mother. How would her mother know anything about this demon when no one has seen him in nearly 1300 years, let alone how to defeat him?
From Fear to Eternity - S1-E13
Visible crew/equipment: When Andy walks into the manor to speak with Prue, just as she tells him it must be bad news, we see the reflection of the boom mic on the glass door. (00:09:45)
From Fear to Eternity - S1-E13
Other mistake: No one, including the cops, seem to think that all the victims' hair turned white is strange, as if getting scared to death actually turned your hair white.
Answer: That was a mistake in the series.
Also, the episode is called 'Babies First Demon' and this alone tells us that it's Wyatt's first time in the field (so to speak) and as the sisters say, they've done a good job of clearing up their own magical messes so far. Nobody really knows how advanced Wyatt's powers are, or will become. That's why the cleaners appear, to nip things in the bud. The Cleaners didn't want to chance that the sisters could clean Wyatt's magic up, just incase they couldn't. Therefore intervening themselves, just in case.