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.
Pre-Witched - S3-E17
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.
Plot hole: When Phoebe and Cole are using the apple peel to find out her true love how does she not recognize that it is Cole? Even with the mask it's very clear that it is him.
Suggested correction: I was thinking the same, but it's possible she thought he was an ancestor/past life of Cole. When she visited her own past life, she recognized everyone there because of their "souls" so maybe she thought the same with him. Although you'd think they'd acknowledge that a little.
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.
Revealing mistake: When Prue is practising using her powers while astral projecting, when Phoebe walks away to go see her in the attack you can see the makeup they used in an attempt to hide her tattoo on the right side of her back. It looks as though she's been bruised there. (00:00:43)
Siren Song - S5-E4
Character mistake: When discussing how best to help Melissa, Piper tells Paige that her birth father was half whitelighter, when he was fully a whitelighter. (00:25:15)
Revealing mistake: The character Ramus (the elder) changes actor when Leo jumps and orbs to get him away from the attack of the Aggressor. The actor's stand-in is visible instead. (00:18:52)
Sympathy for the Demon - S5-E7
Visible crew/equipment: After Paige orbs the potion onto Barbas and Cole absorbs all the powers, in the shot of Barbas getting up from the floor we can see a blue T-mark and an orange T-mark taped to the rug. (00:39:05)
Continuity mistake: When Piper writes the name "Nell" backwards on the castle window she uses two fingers so each letter is doubled lined, but when the name is viewed from the outside all the letters are single lined. Additionally, after she writes the backwards "N" on the bottom right window, in the next closeup of the swords' pointy ends that window is blank. (00:30:20)
Thank You for Not Morphing - S1-E3
Factual error: At the end of the episode the girls are waiting for Victor. He doesn't show up but sends a package containing a home movie. As they are watching it, they see Christmas when they are little girls. Phoebe can't be more than 4 yrs old, 5 at the most. Since she was born in 1975 that would make the home movie take place in approx 1980, but she gets a Wedding Day Barbie, which didn't come out until 1996.
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?
Continuity mistake: Leo says that Piper's past lover is his past life. If it was a past life, in 1924, that means Leo must have died almost straight away to be old enough to qualify as a doctor in WW2. And it wouldn't be his past life but his own past if it was the same life from before he became a Whitelighter. But then he'd also have been 15-20 years older before he died in WW2.
Continuity mistake: In the church scene when Phoebe and Piper are showing Paige how to use her power, Piper says "according to the prophecy, the third sister has the power to move things with her mind, like Prue could." Prue was not the third sister, but the first. Paige is technically The Fourth Sister, but since the prophecy didn't speak of a "Power of Four", she would automatically become the third sister after Prue's death. (01:02:42)
Pre-Witched - S3-E17
Other mistake: During a flash back of Grams in the kitchen she puts a rose in a pot, then Piper walks in, they talk and Piper starts to add some salt and a couple other ingredients into the pot. Grams asks how she knows what to add, Piper says says something about mustard - Piper wouldn't know what's in it already, she just walked in. And she never even finds it strange that there's a rose with a stem in it.
Witch Wars - S6-E21
Continuity mistake: When Paige goes to The Bay Mirror to bring Phoebe potions we see she has 3 different colored potions: green, blue, and orange. She hands the light blue "explosive" to Phoebe, then hands the green one saying it's "acid" but when she hands Phoebe the last potion the camera angle changes and we see that she's again handing her the green one. At this time we see that Phoebe is holding the blue and the orange ones. (00:10:28)
Wicca Envy - S1-E10
Audio problem: When talking about the tiara with a security guard Prue's mouth stops moving mid sentence but the audio continues.
Other mistake: This entire episode the ghost brothers whine that Leo is responsible for them dying and he left them to die, even Leo believes this. It makes no sense. As we see in the flashback even if Leo stayed to help they were blown up moments later and still would have died.
The Three Faces of Phoebe - S4-E14
Continuity mistake: When Phoebe casts the spell to hear her hearts desire about marrying Cole it conjures old Phoebe and young Phoebe. When Leo, Piper, and Paige enter the room they all room perplexed by who the two people, just conjured, are. If this is supposed to be young Phoebe, wouldn't Leo (who has followed all them their whole lives) Piper and especially Phoebe recognize the younger Phoebe immediately instead of being confused by who she is?
Crimes and Witch-Demeanors - S6-E19
Visible crew/equipment: After the opening credits, in the first shot Phoebe is at the stove, then when she turns to walk toward the Book of Shadows we can see the pink T-mark taped to the crew's black mat at the bottom of the screen, which will be where Chris stands shortly. (00:03:25)
The Legend of Sleepy Halliwell - S6-E14
Visible crew/equipment: When Leo and the sisters enter the great hall we hear Gideon call to Leo and thank him for coming, then as the camera pans to the left we can see the T-mark on the floor, at the bottom left corner of the screen. (00:09:25)