Lilly, Do You Want to Know a Secret? - S1-E1
Continuity mistake: In the cafeteria, when Oliver joins Miley and Lilly at the table the food and trays change position, particularly the milk carton. Then when Oliver stands up and announces that Lilly has the two tickets, suddenly the apple has changed trays and the juice box and milk carton are lying flat.
Horrid Henry Tricks the Tooth Fairy - S1-E7
Continuity mistake: When Peter bring his bag's into Henry's room, if you look closely at the wall behind Peter it is pink, but in the next shot if you look to the right, the wall is green - the usual colour, it then reverts back to pink again.
And Then There Were Four - S2-E21
Continuity mistake: After the girls wake up unaffected by the full moon, Cleo asks them how she should wear her hair. Her hands are down when the camera faces her, then they are up when the camera faces the girls. (00:21:15)