Visible crew/equipment: When Phoebe and Paige are trapped against the wall/stairs by the web, the seat that Paige rests on is visible, together with supports under her feet - also note the decorative stair baluster has been removed.
Continuity mistake: When the spider demon cocoons Piper, Paige throws a blue potion (the vanquishing potion) at her, Chris catches it and jumps over the couch, knocks Paige to the floor and Phoebe kicks Chris. The potion falls out of Chris hand and rolls into Paige's open hand, it has now turned yellow (the antidote) Paige grabs it as she stands and throws it at the spider demon again and it has now turned back into the blue potion.