Continuity mistake: In 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: Although the actress has changed, Piper's doctor appears to be the same character as Eva, the shuvani, Paige even says 'we saved her shuvani tribe'. But throughout this episode they call her Eve. And she isn't a different tribe member because Paige tells Piper she already knows of their power, and Eva is the only one who knew from her tribe.
Continuity mistake: In episode 3-9: "Coyote Piper," Piper danced sexily on the bar while the song "Unbelievable" played. She danced only to the one song before her sisters pulled her off the bar. In this episode, Phoebe and Paige physically enter Piper's memory (magically enhanced for accuracy), and a different song plays during Piper's dance, despite it being the exact same video footage.
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: 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: Phoebe says to Paige that she didn't know that Kit was their familiar, that she was just some cat that kept hanging around on the porch. But they learned that Kit was their familiar in episode 3-17 'Pre-witched', and they also said that Kit is male, unlike the woman in this episode.
Plot hole: When Phoebe and Paige are in Piper's memory of her wedding, the warlock steps on the cake topper, crushing it. Piper feels a pain in her heart, and it shows it disappearing in the future, leading you to believe that it will have some significance. Yet, it is never brought up again in the series.
Plot hole: In this episode, when Piper and Leo are preparing the nursery, Leo tells Piper he has been watching her her whole life, and she says "That's a little bit creepy". she acts as if she doesn't already know this but in episode 2-22 'Be Careful What You Witch For' Piper says, "You have been watching me my entire life".
Plot hole: When Paige rearranges the kitchen Piper asks what was wrong with the old system that had worked for the last five years. But when Piper became a neat freak in episode 5-13, 'House Call', she alphabetised all the ingredients in the kitchen, which was not five years before.