Continuity mistake: In 3-5 Sight Unseen, we can clearly see Cole turn the air conditioning very cold and open all the windows so that the Prue, Piper and Phoebe can see the invisible demon, and in season 2 when Prue is turned into a man Phoebe asks "did you fix the air conditioning?" But in this episode Phoebe asks Piper why they have never invested in air conditioning.
Plot hole: In episode 1-2 ("I've Got You Under My Skin"), Alec buys Phoebe a martini at Quake. but then in episode 5-11 ("The Importance of Being Phoebe"), Cole tells Kaya that Phoebe doesn't drink. Then, in episode 5-17 ("Lucky Charmed"), Jason buys Phoebe a "Martini, Dirty" at the end.
Continuity mistake: When Paige follows Phoebe into the kitchen and is trying to convince her that she is telling the truth, Phoebe's right earring is missing in the shots showing both women, but it is there when the shot changes to close ups of Phoebe. It is an awfully large earring to be hidden by her hair in the two-shot.
Continuity mistake: In the episode "A Witch in Time," when Phoebe and Piper are going to Miles' work to get him for the first time, Phoebe runs up the steps to his work and she is wearing leather boots with a skinny heel. Then, when she and Piper are running to where the police shoot-out is, Phoebe is wearing tan Ugs. Then, when they get there and Piper freezes the scene and Phoebe is getting the bullets out of the air, she is wearing the leather boots again.
Plot hole: Piper mentions that Grams banished the Necromancer "sixty years ago" at Patty's Wiccanning. Grams soon thereafter says that the Necromancer has had "almost seventy years" to regain his strength. However, Patty was born in 1950, and this episode aired on 5/4/03, at which time Patty's Wiccanning could not have been more than 53 years earlier.
Continuity mistake: When Paige is telling the others she thinks Lydia is the one Cree was after, she says 'I think Lydia was the one who summoned that dust storm', but none of the sisters were present when the dust storm was summoned. They only arrived afterwards.
Deliberate mistake: In this episode Wyatt has his wiccaning. After all of the vanquishing is done with the Necromancer, it's finally time for the wiccaning and the spell that is said is this:"I call forth from space and time, Matriarchs from the Halliwell line, Mothers, daughters, sisters, friends Our family spirit without end, To gather now in this sacred place And help bring this child to grace." In this spell it is said to bring forth "daughters and sisters" from the Halliwell line, Prue died in the third season and this is now the fifth season, shouldn't she have been summoned as well to bring her nephew Wyatt to grace?
Plot hole: The Sea Hag says at the start of the episode to Mylie that as an immortal being, only she can place the augur shell over her heart to give up her life. But at the end of the episode Necron magically places the shell onto Phoebe and it nearly sucks the life out of her.
Continuity mistake: In the scene where Phoebe dangles the slumlord from the roof, the TransAmerica Pyramid can be seen behind Phoebe and Cole. A subsequent shot, after Phoebe tosses the slumlord back onto the roof, is take from the opposite side, but the TransAmerica Pyramid is still behind them, and is much closer.
Plot hole: In 'Centennial Charmed' Paige orbs to another reality where she loses all her powers. Leo tells her the this is because she was never called as a witch in this world, but Paige had most of her powers before she was called because of her whitelighter blood, so she should retain these. Leo says that Paige has assumed the life of this reality's Paige, but then adds "...or at least the life she would have lived if she hadn't been killed". If alternate Paige had lived she would have had Whitelighter powers, even if she didn't know about them, so our Paige should also have them.