Children of Earth: Day Two - S3-E2
Character mistake: When lanto is in the park and the children all stop the camera shifts to look at a little girl in pink. But in the top left corner there is a young blonde girl still moving and looks to be silently mouthing a word as she steps off the roundabout. (00:32:08)
Children of Earth: Day One - S3-E1
Character mistake: Lois says that Colonel Aduya's uniform "isn't British Army". In fact, it is entirely (and accurately) British Army with the exception of the small UNIT badge over the pocket.
Answer: Several times during the episode, most notably at the beginning when the old grave is discovered, Tosh holds a devise that looks a great deal like the Sonic Screwdriver that she uses to determine the age of the skeleton. However, a search of Google images shows that it is not the same thing.
OneHappyHusky