Plot hole: Cole explains that the demonic power is driving Karen mad because she is human. Cole later has Paige infected with one to drive her mad. This doesn't make sense since Paige is doubly not human, and shouldn't be driven mad. In fact the Charmed Ones have had demonic powers before and were not driven mad, but instead turned evil.
Suggested correction: They all are human, just not mortals.
Size Matters - S4-E5
Continuity mistake: Shortly after Phoebe frees the blonde girl from the clay, she tells her to run "before Gammill sees [them]." But Phoebe hadn't learned the demon's name at any point. Leo and Piper do find out his name, but not until later. (00:20:00)
Suggested correction: Gamill and Finn are talking when Phoebe is at the house. It may be possible that Gamill's name was mentioned by Finn in conversation.
Plot hole: Piper is initially skeptical at Phoebe's theory that the Evil Enchantress could be Paige in a past life, because Paige lacks the Enchantress' ability to summon the elements. However, Piper knows that in Phoebe's past life she had a pyrokinetic power, which she does not have in the present.
Suggested correction: This is not a correction, more of an observation that goes with this plot hole. In season 2 episode 14 'Pardon My Past' Leo explains to the sisters that Phoebe had her active powers taken away, because her past self had used them for evil, but yet the Enchantress does the same with her powers, and Paige still has active powers. It took two years for Phoebe fighting as a good witch to actually gain an active power again, and then it was only levitating. Becoming an empath took seven years. So that doesn't really make sense that Phoebe would be punished for her past self actions and Paige was not.
Possibly Paige had past lives in between the one we saw and the present one. So she could have already atoned for the evil past life in another past life.
Also Paige's active power comes from her Whitelighter side not her witch side, she doesn't have any active witch powers.
Paige's active power comes from her whitelighter heritage, so like Chris and Wyatt, she doesn't have an active witch power, so this active power has nothing to do with her Wiccan heritage and past life as the enchantress.
Continuity mistake: After Phoebe jump kicks a warlock and falls to the ground, there is a blonde woman standing next to them. In the next shot of the warlock, when Piper blows him up, the woman is gone. But all of the mortals had been frozen, so she couldn't have moved. (00:37:40)
Plot hole: According to Paige's "fairy tale" the witch ends up with the prince. If this is really a past life, the sorceress ended up with the prince in the Middle Ages. So why do they have to fix it? Everything was just going the way it did according to her fairy tale, and good magic was obviously still present in the world.
A Paige from the Past - S4-E10
Factual error: On the wall of Paige's bedroom when she was a teenager is a Metallica poster for "Garage Inc.", a CD not released until 1998 although Piper later says that Paige has gone back to 1994. (00:16:05)
We're Off to See the Wizard - S4-E19
Continuity mistake: In the scene where we first see Phoebe and Cole when she's about to leave the apartment, you see she is wearing gold and white high heels but as soon as she reaches the elevator she's wearing black boots.
Plot hole: Leo suggests to Piper that they use their magic to scare Wyke into a confession. In Ex Libris (Season 2) it is established that they can't/shouldn't use their powers to punish the guilty - even if it means saving/helping an innocent. There's no way Leo would suggest such an immoral course of action.
Continuity mistake: Piper does not light the candles before she summons Grams, but in the episode 'PreWitched' (when Grams summons Patty) we see that the candles must be kept alight to maintain the connection with the dead. (00:18:00 - 00:33:30)
Continuity mistake: Paige looks in the Book of Shadows and suggests that the demon they are looking for could be Belthazor, not knowing that Belthazor is Cole's demonic form. But we saw Phoebe making extensive changes to Belthazor's entry in the Book of Shadows in a previous episode, and the changes are not in evidence here. (00:01:40)
A Paige from the Past - S4-E10
Factual error: When we see Paige's 1994 bedroom, she has what appears to be a Bride of Chucky doll. The movie "Bride of Chucky" wasn't released until 1998. (00:16:20)
Revealing mistake: In the teaser, when Leo levitates to hang a picture, he has a major wedgie and the ankles of his pants hike up to mid-shin due to the harness that is used for the levitation effect.
Plot hole: Phoebe and Piper seem surprised at the fact that a white-lighter can impregnate someone, because they are dead. Piper says "how does a white-lighter get somebody knocked up?", but when she went to the future she saw herself with Leo's baby, and Leo told her that he hadn't clipped his wings. (00:46:25)
Size Matters - S4-E5
Continuity mistake: Piper suggests that Paige orb in place, because the clay is still wet enough that it will collapse if she's not there to support it. But when Paige actually does orb, the clay cracks and collapses into powder as if it had been bone dry.
Continuity mistake: After Phoebe has her premonition about Paige at Prue's funeral, demonic bounty hunters show up to "eliminate" Belthazor. We see the funeral hall empty where seconds before Phoebe's premonition, there was a line of people waiting to give their condolences to the girls, Victor, Leo and Cole. (00:12:20 - 00:13:10)
Continuity mistake: The name plate under the photo of Leo at the Veterans Association indicates that he died on November 24, 1942. Paige's research indicates that Nathan and Rick both died on the same day as Leo, but she later finds out that they were buried at the V.A. on November 22, 1942, two days before they are supposed to have died.
Continuity mistake: During Prue's funeral when the demonic bounty hunters attack, one gets thrown into some chairs, which knocks some down. When we see the chairs again in another shot the ones left standing and the ones knocked down have changed. (00:13:25)
