Margaret Blaine, the Slitheen who was reverted back to an egg in season one was due to make a cameo in a scene with the Shadow Proclamation, and Annette Badland even recorded a line of dialogue but the scene was cut.
The episode is a crossover between Doctor Who and its spin-off series Torchwood (2006) and The Sarah Jane Adventures (2007). Writer Russell T. Davies described the crossover by saying "it's simply doing what kids do in their imaginations ... they would think nothing of having their Dalek toys battling Star Wars droids. Why not have all the factions of the Doctor Who universe going into battle together?".
The Stolen Earth is the first appearance of Davros since the 1988 serial Doctor Who: Remembrance of the Daleks: Part Four (1988). Russell T. Davies postponed Davros' return as he thought that "Davros would dominate the Daleks... like plain robots, instead of the scheming geniuses that they are", and used the previous series to establish the Daleks' individual intelligence.
When The Doctor and Donna first arrive at the Shadow Proclamation, the Judoon and The Doctor exhange words in the Judoon's native tongue. This is one of only a few times in the show's history where alien language is not translated by the TARDIS. No explanation is ever given for the lack of translation in this instance.
Alonso Frame's original role in the story was that he would appear when the Doctor and Donna travel to the Shadow Proclamation, assisting them in dealing with his superiors there. He would then journey with them in the TARDIS to the Dalek Crucible, only to be exterminated. His role was given to Harriet Jones.
The scene in the Shadow Proclamation was originally planned to show many more aliens old and new including: Sycorax, Hath, Veespiforms, Krillitane, Gelth, Cybermen, Isolus, Graske, Hoix and even a giant adult Adipose. This was axed because it would have used up half the episode's allotted budget in about 30 seconds.
There was originally a scene where a Dalek Saucer landed at Westminster and one in which the Daleks exterminated the Prime Minister, Aubrey Fairchild, before the Dalek invasion force emerged from the saucer.
When the TARDIS is hurtling toward the headquarters of the Shadow Proclamation, a scene is reused from "The Parting of the Ways" where the Ninth Doctor flew the TARDIS into battle against a Dalek fleet, which bombarded it with torpedoes. Coincidentally, this episode is also centred around a major Dalek conflict.
The script originally featured a lengthy flashback chronicling Davros' youth on Skaro, his experiments on Kaled soldiers, and the explosion which disfigured him. This was previously dramatised in the Big Finish Audio series "I, Davros".
The trivia items below may give away important plot points.
The scene depicting Wilfred Mott firing a paint ball pellet at a Dalek was inserted at the suggestion of Bernard Cribbins; he thought it would provide comic relief in between heavy exposition. Cribbins explained that impairing their vision would be "common sense" owing to the Daleks' lack of limbs and cycloptic nature. The Dalek's response - evaporating the paint ball and replying "My vision is not impaired" - removed a weakness the Daleks had exhibited since their first appearance in Doctor Who: The Dead Planet (1963).