Whatever Happened to Sarah Jane? (1) - S1-E8
Plot hole: When Maria Jackson is running away from the alien creature, she turns left into a metal fencing. The camera shows this seconds before she runs into it, banging on it in frustration. This does not make any sense. She saw the metal fencing, so why did she continue to run into it? Why did she not turn right instead and along the park?
Mona Lisa's Revenge (2) - S3-E11
Plot hole: At the end, all the things and beings that manifested from paintings or drawings are pulled back into their paintings or drawings, including K-9 from Clyde's book. But in the last scene in the Vaults, the puzzle lock can be seen still attached to the Abomination's case, even though it was manifested from a drawing in Clyde's book. The crew probably forgot to remove it after the scene where the paintings went back.