Continuity mistake: As the scarecrow-soldiers advance on the school to do battle, the scene cuts to Sister of Mine, looking out from a school window. There is heavy rainfall outside. When we immediately cut back to the advancing scarecrows, it is a cold, clear night. (00:10:00)
Continuity mistake: When the Doctor comes back to the Cartwright house after imprisoning the Family, Joan walks over to the window and looks out, clasping her hands in front of her. In the next shot, when she asks the Doctor if it's done, her hands are suddenly by her sides, and she is shown clasping them again. (00:34:45)
Revealing mistake: In the penultimate scene, with Tim Latimer helping an injured Hutchinson across a muddy battlefield at night, one of the shots is flipped - in the unflipped shots, Hutchinson has his right arm slung across Tim's shoulders, but in the flipped shot, it appears to be his left arm, and the two young men have switched sides. (00:39:45)
Continuity mistake: When Martha finishes listing off the bones of the hand to Joan, in order to prove that she's a medical student from the future, in a shot facing Joan, Martha's thumb is extended. In the next shot, facing Martha, her thumb is suddenly folded back, as if she was using her hand to display the number 4. (00:12:15)
Continuity mistake: When Sister of Mine enters the school's courtyard after the battle with the scarecrows, her right hand is holding her balloon at the bottom, with the bottom of the string wrapped around her left hand. In the next shot, facing her, her right hand is at her side, with the balloon floating above her left hand. The balloon proceeds to jump between positions until Sister of Mine murders the headmaster. (00:18:00)
Revealing mistake: The pyrotechnic mortars used in the destruction of the Family's ship are visible in the shots leading up to their detonation. As the Family run from their ship through the field, the mortars are visible against the branches behind them. Shortly afterwards, they detonate, creating the illusion that the invisible craft has exploded.
Continuity mistake: When Timothy opens the watch into the girl's eyes, Jeremy Baines shouts "Time Lord", then a few seconds later; "What are we waiting for. Attack!" There is then a shot looking down on the scarecrows, Jeremy and Jenny. If you look closely at Jeremy Baines, it's a different actor playing him. (00:16:20)