Prue and Piper discuss the fact that Piper didn't accidentally blow Prue up. At this point it has been well established that Piper can't freeze Prue and Phoebe because her powers don't work on them. If she can't freeze them, then she shouldn't be able to blow them up either.
After Janna puts the potion on Phoebe's arm in alternating shots her arm goes from having the potion to being red and scratched.
From 22:30 to 23:00, different characters are thrown against a large rock in a fight. The "rock" visibly moves, as if its not really a rock.
Phoebe states that the potion is almost complete, and that they just need an ingredient called ''Billingsroot'' but states that she doesn't know what that is. Billingsroot is Old English for ginger.
During the discussion between Prue, Leo and Phoebe about the witch with the first amulet, Prue states that they got to her too late and Leo tells her and Phoebe that the amulet she was wearing is supposed to ward off evil as well as make her harder to find when she's wearing it. This is why they had a hard time finding her while she was alive. Prue states that they have to find the second witch who has the other half of the amulet, however, they don't know how.
However, if the witches are hard to find, it's never explained how Raynor and evil get past the amulet's cloaking power to find both witches first.