Theory:Doctor Who television discontinuity and plot holes/The Zygon Inversion


 * Why are Clara and her copy using the pulse measuring method for detecting lying ? It is completely arbitrary and a good liar can easily hide it.
 * They're trying to manipulate each other. It's like Russian roulette except you have to guess who's bluffing.
 * Also, the circumstances here cannot really be compared to real life; Bonnie may indeed be able to tell if Clara is lying since they sort of share the same body.