So, in the final episode of series 9, the Doctor is without his TARDIS, it having been left in London during a previous episode.
Not mentioning the beautiful art that Rigsy did to his TARDIS, (which we'll save for another question about whether the Doctor realized who it portrayed (Clara)) —
How did Clara and Me transport the Doctor’s TARDIS using their own? Shouldn't this have been a disaster? If we look at the mini-episode Time Crash when the 5th and the 10th Doctors’ TARDISes crash into each other, it doesn't bode well.
How then was Clara able to transport the Doctor’s TARDIS to the desert?