Factual error: When Phoebe was telling Paige that the energy ball did not come from the other house, Paige says she saw it come through the window. She could not have seen it because she was in the other room and the door to Richard's dad's office was closed.
Continuity mistake: When Chris orbs to the manor after Paige has returned home, his hair is brushed to lay mostly flat and behind his head, with a part on the left side of his scalp. When he comes into the kitchen shortly thereafter, his hair is shaggy and unkempt, with a part in the middle.
Continuity mistake: When the main Calloway throws the clear bottle with the green potion at one of the enemies, the shot cuts and it's now become a white bottle.
Plot hole: When Gith takes the potion from Chris, he ends up stomping on it and shattering the potion bottle - making contact with the potion. We've seen that potions don't have to be thrown by someone who's even a witch for them to work (like when Cole's powers were stripped etc) so why on earth would he do this? And how did it not vanquish him? There are other ways he could have gotten rid of the potion that didn't involve a way that really should have vanquished him.
Revealing mistake: Before Jason Dean is shot outside the penthouse, Phoebe is waving her hands trying to convince him that the world is not real and you can already see blood on her fingers.
Continuity mistake: When Paige is trying to convince Piper and Phoebe that she needs to save Larry's soul, she has the Book of Shadows open to the page on vampires. In subsequent shots, the open page changes to two different demons; but Paige's hands are down by her sides the entire time, so she couldn't have flipped the pages over. (00:26:35)
Continuity mistake: When Phoebe is walking the Dwarf to the door after finding out Piper pulled the sword from the stone, he steps outside and goes into fast-forward, then stops and goes back to normal speed as he sniffs a flower. During this, in the background, you can see Phoebe, who freezes the whole time. (00:18:40)
Continuity mistake: As Piper is talking to Mordaunt at the Round Table, her fringe changes from in front of her face to behind her ear to in front of her face again.
Continuity mistake: When the sisters first see the lady in the lake, the demon off to the side throws a knife into her back, but the knife hits completely straight, as it would if the demon had been directly behind her.
Continuity mistake: When Phoebe is told that Jason asked not to be disturbed she decides to go in anyway, and right before she enters Jason's office the lace-up on the back of Phoebe's top is very loosely tied so we see a lot of skin, but when she's inside Jason's office the lace-up is tied quite tightly so only a bit of skin is seen. (00:11:40)
Other mistake: Paige's spell causes Darryl to acquire invulnerability and uncontrollable super strength. When he opens the door of the squad car, he accidentally rips it completely off. When he tries to put the suspect into the back seat, the man flies through the car and barrels out the other side, taking the other door with him. But immediately before this, Darryl high-fives several of his fellow officers, and they are unharmed. They should have been thrown off their feet and suffered multiple fractures in their hands.
Continuity mistake: When Paige and Phoebe are knocked over by the large monster, the rug moves itself from being spread across the floor to scrunched up under them between shots.
Plot hole: It's shown with the spell that the Halliwells leave for Chris in the attic that if something happens in the past, the future will immediately reflect that change. Chris had changed so much in the past that there should have been at least one thing different that mildly surprised him, even if he was careful to not give too much information to the sisters about the future.
Continuity mistake: In this episode, Chris thinks back to when he went back to the past. When he and Bianca are on the tour of the manor, there are some costumes that have been worn by the charmed ones. But in the episode "Oh My Goddess (1)" Chris tells Phoebe that Paige died on that day, so how could she have worn something after she died? And if she did die that day, Chris would have never met her, since he was not yet born, and could not have learned to orb from her, as he says in "Spin City." However there are other inconsistencies with that story that Chris mentions later, seeming to suggest he lied about this to get the sisters onside. It may not be a continuity error but as it was never fully addressed in the show just what Chris was lying about (and he obviously told some) we cannot be sure.
Revealing mistake: In Chris's flashbacks, it's supposed to be the day he left to come to the future. But his hair is longer than it was in the season 5 finale when he came to the future.
Continuity mistake: When Chris and Bianca go to the manor to get Chris to go to the past, which would end up him appearing in "oh my goddess"; he's only wearing a black shirt and pants. When he arrives to the past in "oh my goddess" he's wearing a jacket, red shirt, and sunglasses. He wasn't wearing that in Chris-Crossed. And he didn't have time to change to that outfit.
Witchstock - S6-E11
Continuity mistake: When Chris orbs Phoebe from Hong Kong, Phoebe raises her arms to hug Piper twice. (00:00:50)
Witchstock - S6-E11
Plot hole: In the opening scene, Chris directs Piper and Phoebe on how to vanquish the amorphous demon. He says that it will attack "fast and hard" as soon as it senses Phoebe's magic when she levitates. But Chris had orbed out of the warehouse and back in, and the demon didn't react to the magic. Later in the episode, it is specifically attracted to a use of orbing, several times.
Witchstock - S6-E11
Continuity mistake: In this episode, it's 1967 and Grams is young and unrecognizable compared to her older self. But in "That 70's Episode," it's 1975 and she looks just like she does today, not to mention that she has two grandchildren. Grams sure ages quickly...
Answer: "Hush, Hush, Hush" Paula Cole.