Plot hole: The innocent who gets Piper's powers uses them to freeze Piper and Phoebe. But even though Piper and Phoebe no longer have their unique powers, they are still good witches; they were still able to scry, and we have encountered good witches on the show in the past who had no powers at all. And by the rules of magic within the show, good witches do not freeze.
There's Something About Leo - S7-E9
Continuity mistake: When Leo is preparing to tell Piper that he's an Avatar, Piper has an orange bowl in her hand and sets it down on the table. In the next shot, she's holding the bowl again and sets it down a second time. (00:17:45)
Little Box of Horrors - S7-E18
Character mistake: Katya (as Nina) says that Pandora's Box is "a gift the gods gave to Prometheus." But the Box was given to Epimetheus, not Prometheus. Epimetheus ignored the warnings of Prometheus, his brother, and accepted Pandora herself, who bore a box, as a gift from the gods.
Continuity mistake: For season 7, episode 5. In the beginning, Piper is wearing a top with the blue skinny strap on her right. For the rest of the episode, you can see the strap on her left.
Continuity mistake: When Piper is talking to Cole, they show the other Piper on the couch. Whenever you see Piper talking, you can see that the other Piper's legs change position throughout the shot. They go from being straight to both legs bent to one leg bent to straight. (00:18:00)
Visible crew/equipment: Just after Paige casts the spell to rid Piper and Leo of the gods inside them, the tip of the boom mike is just in shot above Paige's head. (00:33:10)
Charrrmed! - S7-E4
Revealing mistake: When Leo is on top of the bridge meditating; the water shown in the background is not moving. Also, cars on the bridge move, but often change speeds rather dramatically (sometimes moving fast and other times moving incredibly slowly).
Visible crew/equipment: When Paige explains to Phoebe that someone tried to kidnap baby Chris, when the shot is on Paige you can see the white tape of the actor's cue marks on the floor. (00:29:05)
Something Wicca This Way Goes - S7-E22
Continuity mistake: Phoebe's shoes change between shots. Near the end, while fighting Zankou in the basement, he hurls the sisters to the ground and Phoebe is shown wearing sandals. When she stands up, she is now wearing sneakers.
Continuity mistake: At the beginning of the show when Piper comes into the kitchen to help Paige, she is wearing slippers. In the next shot, when she is by Wyatt's chair, she is wearing flip flops.
Someone to Witch Over Me - S7-E7
Continuity mistake: In episode 7-7: "Someone to Witch Over Me," Piper is killed by the demon Sarpedon's metallic claw. When the claw strikes her, she falls back with her arms behind her, landing partially on her palms, allowing her to complete the fall by sinking gradually to the ground. Then there is a cut to a closer shot, and we see her fall again. The second time, she falls directly into a more prone position with her arms raised and the backs of both hands facing the ground.
The Bare Witch Project - S7-E2
Continuity mistake: At the end of the episode it is not Alyssa riding the horse to the café. Alyssa has a tattoo on her right ankle, which when we see when camera pans up the right leg the person riding the horse has no tattoo on the right foot, but when Alyssa rides away you can see the tattoo she has going round her right ankle.
Continuity mistake: Midway through the episode, the Seer is looking through the sisters' photo album. Several of the photos actually include everyone who was present for the events depicted, leaving nobody to take the photo. And since the events were shown in various episodes, we know that no photo was taken at those times by any automated method.
Continuity mistake: In this episode, Phoebe told Drake that she "can't believe it's been three weeks already", but Drake said in "Carpe Demon" that he only had two weeks to live.
Continuity mistake: In the beginning when you see Piper and Paige sitting in the car talking on their cell phones, Paige has hers in her right hand. You can see she has a ring on one of her fingers. In different shots the ring is gone. (00:00:30)
Continuity mistake: In this episode they say an alchemist has the power to control the dead but not bring them back to life. However, in the season three episode "Coyote Piper," the alchemist brings both the body in the alley and Piper back to life.
Continuity mistake: In the second to last scene where Piper tests her powers on the lamp and Phoebe is cleaning, you can see Piper's bra strap when she blows up the lamp but when she turns to face Phoebe its covered. Through out the scene it's covered and exposed without her ever adjusting her shirt.
Something Wicca This Way Goes - S7-E22
Continuity mistake: Tim's eyes keeps changing from opened to closed at the morgue with Zankou.
Plot hole: When Grams is summoned for Chris's wiccaning, she reminds Piper of "the talk" they had when she was a teenager, about how important and special being a witch was to Grams and how it would be to the girls someday. But in the first episode, the girls have no inkling they are witches, and when they find out it's passed through the maternal line, they wonder if Patty or Grams was a witch - suggesting that they aren't sure or have no memories of them as witches. I know there was some memory altering at certain points, but why would Grams have a conversation specifically about how great it is to be a witch and then erase that?
Answer: That was a mistake in the series.
Also, the episode is called 'Babies First Demon' and this alone tells us that it's Wyatt's first time in the field (so to speak) and as the sisters say, they've done a good job of clearing up their own magical messes so far. Nobody really knows how advanced Wyatt's powers are, or will become. That's why the cleaners appear, to nip things in the bud. The Cleaners didn't want to chance that the sisters could clean Wyatt's magic up, just incase they couldn't. Therefore intervening themselves, just in case.