Continuity mistake: When she sees the little boy's ghost, Gwen's hair alternates repeatedly between neatly-combed and windblown/messy, depending on the shot. (00:03:30)
Continuity mistake: While she's talking to Mary in the flat, Toshiko's hair keeps changing between shots, going from combed evenly to split apart with one section hanging in the middle of her forehead and the rest brushed back. (00:31:30)
Continuity mistake: In the opening scene, Gwen has a long, loose strand of hair hanging over her left temple - but every time the camera angle changes, it disappears. (00:01:00)
Out Of Time - S1-E10
Continuity mistake: John is about to eat liver and potato with Emma before she storms out saying, "I don't like liver". While they are talking, the potato is facing Emma and Gwen. After Emma leaves, the liver faces Gwen and the spot where Emma was.
Countrycide - S1-E6
Continuity mistake: In the pre credits sequence, when the lady gets out of her car the antagonist slashes her rear tyre however after the antagonist is attacking her inside the car we see a rear shot of the vehicle, and the tyre is fully inflated.
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