Plot hole: One of the sisters asks why the familiar doesn't just jump in front of a bus 5 times, another responds with "we're the only ones strong enough to kill him." If they are the only ones strong enough to kill him, then how come two scenes later he falls on a knife during a fight with Phoebe and dies? If a knife can kill him then it doesn't make sense that he seeks out the charmed ones.
Continuity mistake: The timeline in the episode is inconsistent. Right after the first courtroom scene, we see the three sisters at home, and Phoebe says that "Cole was an angel in that courtroom yesterday." Later, Cole says that he regrets the criminal being let go, "today." But they are talking about the same events.
Revealing mistake: When Phoebe throws the potion at Cole's coat, the vial doesn't shatter, even though it sounds like it. Watch closely, and you'll see the purple, unbroken vial bounce off the coat and away out of shot without any of the potion touching the coat.
Continuity mistake: When Prue talks to Piper after stopping her phone conversation, she tells her that "the Sin Balls work a lot faster than [they] thought. Once infected, the victim only has a few hours before it drives them to total self-destruction." However, this is almost verbatim what was written in the Book of Shadows. It could be easily read by the viewing audience when the book entry was shown. So all three sisters should already know this.