Theory:Doctor Who television discontinuity and plot holes/Attack of the Graske


 * If the TARDIS is following the Graske's trail, then how can it arrive before him?
 * It follows his trail to the right timezone and then has to wait around until he materialises.


 * The map of Victorian London looks more like a map of modern London.


 * If the Graske want to conquer Earth by replacing its population then why does the Graske we see replace a modern day person and then travel back in time to replace a Victorian person? Why not just try to conquer Earth in one era rather than two eras?


 * How does the Doctor know that the Raxicoricofallapatorian is from the Slitheen family?
 * Different families may have difference skin colors (Slitheens are green, Blathereens are orange, etc.