- The Doctor's cottage exists in both Doctors' universes.
- The Doctor refers to his current repairs of the TARDIS as a sort of "ten-thousand year service". The temporal equivocator is low on liquid mercury.
- Edward IX is king of England in the first parallel Earth.
- The Doctor states that cars with solar powered engines won't exist on Sarah Jane's Earth for another century (ca. 2070s). At least one such engine exists in the first parallel Earth.
- The Doctor of the parallel Earth is evidently native to the planet, as he does not recognise the TARDIS and has no knowledge of extraterrestrials or space travel.
to be added
- The Doctor previously met counterparts of individuals from his reality in a parallel universe, on Inferno Earth. (TV: Inferno)