Theory:Doctor Who television discontinuity and plot holes/The Family of Blood


 * In the dance, why doesn't the Family shoot Martha? She wouldn't have enough time to react to the gun being fired, as seen later on.


 * They may have been afraid of hitting and killing Mother of Mine, who is after all being used as a shield by Martha.


 * Why didn't Martha just keep the fob watch in her pocket the whole time?
 * Because it is programmed to rewrite human DNA. Martha is Human, and is saturated with Arton Energy as Smith is. We saw what it did to Tim. It'd do the same to Martha.
 * No it wouldn't, the only reason Tim heard the watch is because he had a low level telepathic ability; that's why Joan didn't hear it.
 * Maybe he felt attached to it when he first changed and it became part of his identity? He did check on it quite often.  Maybe Martha figured she shouldn't take it from him because he felt it was an heirloom (with his false human memories) and may miss it and that may have caused trouble for their relationship during their transition and by the time they had settled in as maid and teacher she figured it was safe enough.


 * What happened to the scarecrows?
 * Without the Family to animate and control them they reverted back to their previous state.


 * Why didn't the Family of Blood die after they were imprisoned for eternity?
 * The Doctor wanted them to pay for what they had done, so he used his knowledge to grant them immortality in a way they would not like. The forms of their punishments may also have made them immortal, i.e. being frozen, time slowing down at the event horizon of a collapsing galaxy, and the unknown properties of the mirror dimension.


 * If all that is required to defeat the Family is to distract them long enough so as to tamper with the controls of their spaceship, rendering them effectively helpless, why does the Doctor choose to employ such an overcomplicated plan that puts a lot of innocent humans in danger and only leads to the very killings for which the Doctor feels obliged to punish the Family so severely for at the climax?
 * They were actively shooting at him when he ran from them, and had to escape and hide from them before he could get them to such a point.


 * Considering the Family's ship was theirs, why weren't they aware that the Doctor having pushed all the switches would have had a bad/unwanted effect on the ship?
 * They weren't paying attention and didn't expect Smith to have set it up.


 * No explanation is given for how exactly the Doctor manages to capture and punish each member of the Family at the end of this episode, apparently demonstrating the possession of unprecedented powers on his part.
 * The Family realise that they should stop, they look up at the Doctor after the explosion and, realizing they have no way to escape, possibly give themselves up to him.


 * The Family no longer had their ship and weapons. They were helpless.


 * It isn't possible that the Doctor can trap Sister of Mine in every mirror because a mirror is basically an object with a reflective surface, in fact, you see things by the light being reflected off them, so everything except pure black is a mirror.
 * We are talking about a species that has harnessed the energy of black holes to travel through the space/time continuum and used bowships to fight giant vampire bats in space. It may not be possible per se, but the Time Lords were capable of a lot of impossible. That, and the Doctor is definitely not one to mess with. If anyone could find a way to trap a body within the confines of what we call a mirror for all time, it'd be him.


 * The mirrors probably work in the same way the reflections do in the Curse of the Black Spot.


 * Keep in mind that in the Whoniverse, it's somehow possible to use mirrors to travel in time and through dimensions (Evil of the Daleks, Warriors' Gate, at least two EDAs, at least one BFA, and at least one NSA). So, either we don't understand everything about mirrors, or they work differently in the Whoniverse.


 * Also, the NSA Martha in the Mirror confirms that this is meant absolutely literally: the Doctor figures out that the Mortal Mirror isn't a real mirror because he can't see Daughter of Mine in it.


 * How can Father of Mine live forever if all the Doctor did was chain him?
 * Maybe the Doctor did two things—made him immortal, and chained him—but only explicitly mentioned the latter (since he'd already separately said that he made sure they'd all live forever).


 * Otherwise, the chains or the shaft presumably did something to keep him from dying. We've seen things like the compressed time streams in The Girl Who Waited, DT fields in Anachrophobia, and even the TARDIS interior in various stories that can stretch out objective and subjective time differently, so he could have lived a subjective infinite amount of time even though his body only aged an objective finite amount of time, or something like that.


 * Perhaps the chains are merely an ironic definition of immortality as well. The chains are indestructible/carry special properties that render them "immortal" but not Father of Mine.  Therefore, Father of Mine spends the rest of his existence so close to immortality but not able to actually have it.


 * If The Doctor can change his smell, as seen in the climax of the episode, Why didn't he just do that for three months? The Family would have died, and he wouldn't have had to risk any humans' lives.
 * Maybe it was temporary. The family would still sense Time Lord presence after a while.


 * What happens when someone tries to vandalise that scarecrow or unmasks it? Also this is a little odd but Son-Of-Mine says that the doctor visits Sister-of-Mine once a year every year, does this mean he only looks in a mirror once a year and just by doing so visits her or is it a special act that he does separate from actually looking at himself in a mirror by chance?  Also wouldn't the event horizon of a galaxy not actually go on forever?  It might feel like it but eventually she would be crushed into a singularity or torn to atoms wouldn't she?  (I think all of those are good for being under only one bullet, being about the fates of the Family and all)
 * To Mother-of-Mine it would still feel like a long time.
 * Due to special relativity, inside the event horizon, time freezes, its messy but basically you would feel as if you were just inside the horizon for ever.


 * The doctor could have checked in the future if the scarecrow would be vandalised and then put it there after knowing nothing would happen.


 * Not so much a discontinuity as such, but the Doctor's behaviour in punishing the Family is contrary to everything we have learned about the Doctor, and the Tenth Doctor in particular.
 * This is the behaviour of the Seventh Doctor in the Virgin New Adventures. Many people strongly dislike these books for that exact reason. This is the way Cornell wrote the Seventh Doctor in the books, and it is his preferred idea of who the Doctor really is. However, it is, as you say, completely contrary to the Doctor's normal behaviour, and particularly jarring for the Tenth Doctor.