Theory:Doctor Who television discontinuity and plot holes/The Woman Who Lived


 * When Me reveals her plan to use someone's death to open the Eyes of Hades, the Doctor mentions that death rips a tiny hole in the universe, thus implying that death is unnatural. However, earlier in the season (UtL/BtF) the Doctor condemns the Fisher King for hijacking the natural process of life and death. Breaking this cycle was so devastating for timespace that the TARDIS wouldn't go near the 'ghosts.'
 * Those two concepts aren't necessarily contrary. The "tiny hole" the Doctor speaks of (possibly metaphorically) may well be a natural part of the universe's cycle, so long as it's not exploited by a massive energy source, as it was here.