Theory:Doctor Who television discontinuity and plot holes/Rosa


 * The Doctor's TARDIS has a perception filter that means people "walk right past it" as the Ninth Doctor once said and many do. Yet, Krasko breaks through the filter despite not even knowing the TARDIS was in the area, thereby was not looking for it (a key component to breaking the filter's hold on passerbys) so: How did he notice the TARDIS?
 * Krasko's case, as stated by the Dcotor, had a perception filter. It is probable that Krasko is able to view objects through the filter somehow. Furthermore, he knew what TARDISes were, meanign he would most likely be aware of the filter, because of his case.