Pool Party (aka Pilot) - S1-E4
Audio problem: When Lizzie goes into the living room while her Mum is on the phone, she takes the remote control from Matt. We can then hear Matt shouting tales at Mrs. McGuire, but if you watch him his mouth isn't moving at all. (00:12:10)
Continuity mistake: At the beginning of the episode when Kate is inviting Lizzie, Gordo, and Miranda to her party and they read the invitation it says she is turning 14 but in Season 1 Episode 30 Gordo's Video, in Gordos video Kate tells Claire she's already 14.
Suggested correction: Kate soon turning 14 is a running gag in the show. She is canonically hiding her real age, so it makes sense that she lied about her birthday party and only confessed to her best friend about her real age. This running gag becomes more clear when Mrs. McGuire asks how old Kate is turning, to which she replies with "14" and Mrs. McGuire starts chuckling and says "sure."
Suggested correction: When Lizzie goes into the living room while her Mom is on the phone, she takes the TV remote away from Matt. We can then hear him shouting at Mrs. Mcguire until Lizzie tries to take her hand and place it over his mouth.