Theory:Doctor Who television discontinuity and plot holes/The Face of Evil


 * Even while accepting that the Doctor plans to be locked into the particle analyser with Leela (implied by the way he palms the mirror in the preceding scene), his method of escape from it depends upon three implausible coincidences: 1) That the Tesh would have tied him up with the mirror still in his hand. 2) That the laser would begin its analysis by firing at his hand (which would seem ill-advised of it, as the prisoners are restrained into the machine by their hands). 3) That damage to the laser would, conveniently, result in the machine setting the prisoners free (rather than simply leaving them pinioned until the laser could be fixed).
 * 1) The Doctor was able to keep the mirror discreetly in his hand. 2) & 3) The Doctor was familiar with the technology and its behaviour.


 * In Part Two, how does the Doctor know where the bridge into the wall (through the teeth) is? (He doesn't remember his last visit until after they've entered the wall - if there's anything to remember anyway; he seems surprised when Leela asks how a signal can be getting through, although this may be because he can't remember the concept at that point!)
 * He figured out it was a beamed transmission and tracked back the beam. And he probably guesses the teeth is the way to go because it's the most obvious place.


 * The scene in episode one where the Doctor uses the alarm clock to divert Xoanon's id creatures seems to imply that they walk and have feet with which they stomp on things. Yet the climax of episode three shows that they are only disembodied floating heads.
 * They are manifestations of Xoanon's subconscious, making the form they take infinitely mutable.


 * At the end of Episode 4, how does Leela know how to operate the controls?
 * She doesn't. It appears that she is pressing any controls, wondering what they are, her being so primitive. Plus, the Doctor knows that she shouldn't "touch that", yet she clearly doesn't.