At the end of "the unicorn and the wasp" the Doctor shows Donna an Agatha Christie book that was published in the year 5 billion. Well here is the mix up, in series 1, the Doctor takes Rose on her first journey to the end of the world. He had taken her to the year, wait for it, the year 5 billion, now how would the human race publish an Agatha Christie book the year the earth died?
It is one of the biggest Doctor Who stuff ups yet!
