Age of Steel - Plot - Continuity

Continuity

• Lumic's expression of "Excellent!" is a reference to the off-key rendition of the word that the Cybermen have used in previous stories (beginning with the Fourth Doctor story Revenge of the Cybermen).
• The Doctor's comments about Cybermen in his universe confirms that the origin of the Cybermen in this universe is not a rewriting of the origins of the Cybermen on Mondas as established in The Tenth Planet. Similarly, this leaves the Big Finish Productions audio play Spare Parts intact.
• Mickey refers to his "tin dog" status, as in "School Reunion", a comparison to the Doctor's former robot companion K-9.
• The Doctor refers to attacking Cybus's factory at three points: "Above, between, below." This echoes an ancient Gallifreyan nursery rhyme that refers to the three possible entrances to the Tomb of Rassilon (The Five Doctors).
• The storage of the converted Cybermen in the cooling tunnels is similar to the events of The Invasion, where the Cyber-army was hidden in the sewers of London. Cybermen were also kept in cryogenic freeze in The Tomb of the Cybermen. In The Invasion the Doctor also used emotions to defeat the Cybermen.
• This episode is also the first time since Attack of the Cybermen that gold has not been used as a weapon against the Cybermen. The Cybus Industries tie-in site makes reference to earlier prototypes having an "allergy" to gold, stating that this was eliminated after further improvements of the Cyberman body.
• Elements similar to Spare Parts include the converted Jackie being aware of her previous identity as a human (as Sisterman Constant and Thomas Dodd were in the play). Sally Phelan's moment of awareness is also similar to Yvonne Hartley in the play.
• Although a Cyber-Director appeared in The Invasion, and was an immobile unit, the first Cyberman Controller appeared in The Tomb of the Cybermen (and later in Attack of the Cybermen) as a differently designed Cyberman with an enlarged cranium.
• The Doctor says, "I'm sorry. I'm so sorry," to the dying Cyberman, Sally Phelan. He has used these words before in the 2006 series, when discovering a diseased 'New Human' in "New Earth". The President said this in the previous episode, "Rise of the Cybermen". The phrase recurs in subsequent episodes.
• The Doctor's speech to the Lumic Cyber-Controller while walking round in circles is reminiscent of the speech he used against the Sycorax in "The Christmas Invasion" and to the Clockwork Droids in "The Girl in the Fireplace". It is also similar to a conversation about emotions between the Fifth Doctor and the Cyber Leader in Earthshock (1982).
• Mickey leaves in this episode, choosing to assume the role of his deceased doppelgänger Ricky and continue his fight against the Cybermen, making him the first companion in the new series to leave the TARDIS crew by choice. Adam Mitchell was expelled from the TARDIS in "The Long Game", and Jack Harkness was left behind at the end of "The Parting of the Ways".
• As the Doctor says goodbye to Mickey, he jokingly calls him "Mickey the Idiot". This was a nickname the Ninth Doctor used for him more harshly. The Doctor also refers to this nickname when, during his debate with Lumic, he continuously uses the word "idiot" while trying to drop clues to Mickey.
• Mickey mentions that he "once saved the universe with a big yellow truck". This is a reference to "The Parting of the Ways", when Mickey opens the time vortex on the TARDIS using a tow truck, thereby allowing Rose to return to the future and defeat the Daleks.