Laura June Hudson plays the ill-fated Elderly Woman. She had been a BBC Costume Designer on the original show, working on eight stories between 1978-81. Tom Baker declared her his favourite, loving her operatic style.
Playing Timothy Drake, discoverer of The Devil's Chord, is Jeremy Limb. He's the son of 1980's Doctor Who (1963) composer and BBC Radiophonic Workshopper Roger Limb.
In the manner of earlier Doctor's shouts of "Allons-y!" or "Geronimo!", the Fifteenth cries "Hadi ama!" - Turkish for "come on!"
The TARDIS elects to materialise in a spot recreating the cover of The Beatles' 1969 album "Abbey Road"; even the white VW Beetle on the left (reg. LMW 281F) is present. This is all clever camerawork, as the scene wasn't shot at Abbey Road at all.
The billboard at the top of Abbey Road is for 'Chris Waites And The Carollers'. This is part of the fictional history of the band John Smith And The Common Man - a song by them features in the first episode of Doctor Who and there are numerous references to them in in The Whoniverse.