I'm wondering where the call to the other Doctors came from (the Tardis perhaps but she is very rarely understood by any Doctor).

Why are ALL the Daleks and ALL the Time Lords in the universe all concentrated around one planet ? (I thought Arcadia would be a refugee colony planet) . . . Why does it take the Doctors 3 (or 13) of him and his Tardis) to do this rather than the Billions of Time Lords and Tardises on the Planet ? . . . . . What was the need for the Zygons sub-plot other than to pad the episode out (or pay for the suits to be used in later Zygon stories or to justify the new slightly different Zygon action figure) ? . . . . . etc........