Plot hole: According to the family tree viewed in this episode, Penny "Grams" Halliwell was born on 6/23/1937, and her daughter Patty, the Charmed Ones' mother, was born on 4/5/1950. In addition, Patty's father was born in 1930. So, according to this, Penny gave birth to her daughter at age 12, while married to a 20 year old man. That's quite outlandish, to say the least.
Continuity mistake: When Piper and Leo confront the genie at the restaurant, the genie is eating food as fast as he can. At one point he gets a line of pasta sauce on his cheek. The shot changes, then goes right back to him only now the sauce is gone with no time for him to have wiped it off, especially since his hands are full of food.
Continuity mistake: In 'Morality Bites', Phoebe has her premonition about being executed while watching a news report on a baseball player, right after she and the others punish Pratt. When she returns in time at the end of the episode, they all watch the news report first and only afterwards look out the window and see Pratt.
Continuity mistake: In the teaser, Phoebe took off her messenger bag while she was sitting in the chair talking to Prue, and she left it there when she went up to get the door. For the rest of the scene at the house, including when Phoebe and Prue ran out of the door, Phoebe was not wearing the bag. Then, when we saw them outside immediately thereafter, Phoebe was wearing the bag again.
Continuity mistake: After Phoebe kisses Billy, she sees that the makeup over his lips has washed off and that they're in black and white again. While she applies more to him, the phone rings, Billy turns his head, and his lips are normal. In the next shot, they're back to being in black and white.
Continuity mistake: On 2/17/1999, Phoebe realizes that her past self, P. Russell, died on that same date in 1924, and was the same age as Phoebe is now. According to the family tree she is looking at, P. Russell was born on 7/2/1894, meaning that she was 29 upon her death. But Phoebe was born on 11/2/1975, according to that same family tree, making her only 23 at the time of this episode.
Plot hole: When teenage Prue has run away with the demon, and Phoebe and Piper find her in the park, teenage Prue is 'killed'. Her sisters drive her home to get Leo to heal her, but shouldn't they have just been able to call to Leo to orb to them when Prue was first hurt, and heal her in the park, and save driving back to the Manor and risk Prue dying?
Continuity mistake: When Prue leaves Buckland's, she's wearing a red tank top, but when she arrives at Camp Skylark, her shirt is different, both in style and color. She can't have stopped to change, because it's mentioned she left the auction house and headed directly to the camp.
Plot hole: In this episode the Charmed ones state that the ghost can only be vanquished by a potion on the ghost's bones (grave) or if the haunted object is destroyed. But in episode 1-20, "The Power of Two", Prue has to die herself to be able to vanquish the ghost with a spell, and we learn then that this is the only way to vanquish ghosts.
Other mistake: After Sam uses the powder on the sisters, erasing their memories, they're visited by Leo who starts to say "he must have gotten the powder" and one of the sisters finishes with "our mother." But in a later episode we learn all white lighters have this powder.