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: 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)
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)
Visible crew/equipment: After Piper summons Grams and then Patty appears as well, when it cuts to Darryl and Cortez entering the manor, the blue and white T-marks taped to the crew's black mat are visible, at the bottom of the screen. (00:34:00)
Audio problem: When Piper, Paige and Phoebe run up to the attic to run from Shax, Piper says that they're about to find out if Paige is their sister, her mouth is shut when she is supposedly saying the sentence.
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)
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)
Continuity mistake: In the scene with Paige and Jordan Bridges' character, nearer the end, when they are sitting on the couch and his possessed character leans in for a kiss, from the back shot, he leans in and his head is tilting towards his right shoulder (you see part of his profile and the back of his head and Paige's face); when they change the shot so you see the front of his face and the back of Paige's head, his head is tilted back towards his left shoulder.
Continuity mistake: After the "dirtbag" is brought back to the manor and Piper is ragging on him, Piper gets very angry and decides to blow her husband up. Less than a minute later, Cole says "Back away slowly, Leo." Leo says "What?" and Cole says "She's becoming a fury." Then it shows Pipers hands, which now have long black fingernails, but they just suddenly show themselves right when Cole decides to show up and say she's becoming a Fury. When she blew Leo into orbs there were no long black nails. (00:25:35)
Revealing mistake: When Phoebe and Paige use Cole as bait to lure Piper to the manor, Phoebe levitates and kicks two furies at once. When they show the front shot of her kicking these two furies, we can see Alyssa Milano's stunt double. (00:34:25)
Continuity mistake: When Piper is grieving Prue's death in the mausoleum, Leo's hand moves from cupping her face to resting on her shoulder blade between shots. (00:37:15)
Other mistake: When Piper and Paige are talking at the Social Services building, Paige talks about one of her coworkers, but in the closed captions, the speaker is mislabled "Piper." (00:41:30)
Continuity mistake: During the opening, Piper, Phoebe and Cole are in an SUV and going to find a demon. A shot from in front shows that there is no rearview mirror in the SUV, just a white mark on the windshield. When they turn into the parking lot however, the rearview mirror has returned.
Continuity mistake: When Anling unmasks Yenlo, Yenlo's left hand is covering his wound. In the next shot, his hand is down by his side. (00:03:50)
Revealing mistake: In the beginning of the episode, Yenlo and Anling are fighting with swords. After Yenlo says, "I'm going to kill him, Anling. And then I'm going to kill you," Anling stabs him with her sword. Yenlos' wound is very bloody, but there is no blood on Anling's sword at all. (00:04:25)
Continuity mistake: After Phoebe and Paige have switched bodies and Phoebe is trying to teach Paige how to levitate, Phoebe's hair switches from her shoulder to her back then to her shoulder again. (00:20:15)
Plot hole: When Yen lo enters the manor in the attic. Where did the water on the floor he comes through come from? Windows were closed, no visible leak, and the sister took precautions to make sure there was no water in the house. Also after he attacks and gets the dragon blade, he exits the house through the sink filled with water. Piper had already said to make sure there was no surfaces of water in the house and had Phoebe and Paige shut the water main off.
Suggested correction: There is a previous scene that shows a visible leak in the windows and an obvious puddle of water on the floor of the attic. This is the same puddle they later enter limbo through. As for the sink, Phoebe (in Paige's body) explains that she had been soaking potion pots and forgot to drain the sink. Turning off the valve wouldn't dissipate water that is already in the sink.
Other mistake: Yenlo explains that he escaped limbo through the water in the clouds. And the yen master says there is no other water around. So why do the girls come in through a cave? If they have to leave through the water in the clouds they should enter through the clouds.
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.