Plot hole: The book that hit Phoebe 2 in the head actually hit her on the shoulder, not the head. She should not have turned dumb.
Dinner Party - S1-E3
Audio problem: When Barb mentions to the Campbell's about tiny servants, her mouth does not match with what she's saying.
Continuity mistake: When you see Barb back from CostClub she has at least 7 boxes. When she is seen again she has 3.
Continuity mistake: Rusty throws his rattle on the ground, and when Nora and Billy push the strollers to the balloons, it is still there. But after this, it disappears for the rest of the episode.
Continuity mistake: When Phoebe and Max are tied together, the whip starts to cause sparks to fly in the the air. Then, a lightning bolt appears and Electress (really Barb) pops up and says "shocked to see me?" and the whip isn't sparking anymore.
Suggested correction: Her presence stops the whip from sparking as it was her weapon.
But wouldn't the fact that Max and Phoebe are touching the whip also keep it from sparking? True, it's not their weapon, but they are "supes," so their powers should have prevented it.
Revealing mistake: When Max pushes the stroller into his house, look into the stroller and you can see a baby doll, not a real baby.
Visible crew/equipment: When Hank is bribing Billy and Nora with the giant chocolate chip cookie the camera is reflected in the window on the door.
Revealing mistake: When Phoebe freezes the secretary, you can see that she is frozen before Phoebe's "freeze breath" gets to her.
Nothing to Lose Sleepover - S1-E16
Continuity mistake: When Max and Dr. Colosso jump onto Phoebe's sleeping bag there are 2 pillows, a light blue pillow, and a dark blue pillow. When Max lands on the sleeping bag the dark blue pillow disappears.
Welcome to the Family Part 1 - S2-E24
Revealing mistake: When the father is launched down the stairs he's very obviously been replaced by a dummy. Watch how his left arm bends awkwardly.
Continuity mistake: When Phoebe summons her suspects who she thinks might be the Rebel Raptor and when only Gideon showed up, he is holding red and white flowers in a bouquet, but in the next shot, he is holding yellow and purple flowers.
Are You Afraid of the Park? - S3-E5
Other mistake: When Nora lasers Phoebe her clothes have holes in them but Nora lasers Billy all the time and his clothes are fine.
Continuity mistake: When Phoebe makes the backpack slide it turns around 180° between shots.
Continuity mistake: After the courier trips and falls the backpack moves closer to him between shots.
Thunder Van - S2-E1
Other mistake: The Thunder Van is claimed to be soundproof, but when Hank finished pranking the kids, Phoebe could be heard talking to Barb from inside it.
Revealing mistake: When the whip is sparking, no black marks are left on the floor.
Continuity mistake: After Max's flashback, Nora's pencil changes position on her notepad.
Continuity mistake: When Max leaves with his ten-foot pole he knocks a lamp off a table and breaks it. When he returns the lamp disappears from the floor.
Revealing mistake: When Max is strapped to the armchair it becomes obvious on at least three occasions throughout the scene that the strap is not secure and he can escape the chair by pressing down into the fabric, but chooses not to.
The Girl with the Dragon Snafu - S2-E23
Continuity mistake: When Hank gets frustrated, he pulls the doorknob off the new bathroom. When he is standing on the rug, we can see that the doorknob is back on the door.