Before writing the script, Robert Shearman asked his girlfriend what she thought were the silliest things about the Daleks. He then took the responses he got - that they couldn't go upstairs, that they had that silly plunger, that they couldn't see anything behind them, that bullets could damage them, etc - and had the characters actively invoke them in the story. And then had the Dalek completely subvert the expected weaknesses and even use them to kill said characters horribly.
The Doctor's interaction with the Dalek was originally written to be just mocking and flippant. Christopher Eccleston decided to pour in incredible amounts of rage and pain as well. Robert Shearman was briefly miffed, then delighted once he realized how well it worked.
Robert Shearman had to write a second version of the script because it was not initially known if the new series could obtain the rights to use the Daleks from Terry Nation's estate, so he had to create an alternate alien race that would have been used had the Daleks not been available. The alternate monster was a spheroid creature akin to a sadistic child which was actually a mutated version of humanity from the end of time. Although this alternate concept was shelved, it would later be used for the Toclafane in the series 3 finale, Doctor Who: The Sound of Drums (2007)/Doctor Who: Last of the Time Lords (2007).
The fictional Geocomtex website lists under its Products section Node Stabilized (in Lupus and Nocens variants). Lupus is Latin for wolf and nocens for harmful or bad. Interestingly, they also offer Argentum Ordnance, otherwise known as silver bullets.
The titular dalek was operated by three people. One actor was inside the dalek casing to move and rotate the body. A second was moving the head and eye stalk and operating the lights by a radio controlled remote. The third was performing the voice and gesturing to the remote control operator to time the lights with the voice. In the original series, Doctor Who (1963), the daleks had only two operators; one performing the voice and the actor inside the casing doing everything else.
Henry Van Statten was originally named Will Fences in joking allusion to Bill Gates. This was later changed to Mr Duchesne, but Russell T. Davies was concerned that this was too difficult to pronounce.
This episode would be the only story in Russell T. Davies' years on the show in which the Daleks would be involved in only a single episode of said story. All other Dalek storylines would be spread across two episodes in the future.
The episode was placed in the third production block, along with Doctor Who: Father's Day (2005) and Doctor Who: The Long Game (2005), the latter taken out due to delays in special effects creation. The episode's placement in the series was intentional so as to stave off an anticipated mid-series drop in viewership, although the BBC suggested that the episode be the premiere.
Van Statten is heard to utter the curse word "goddamn" - the first time this word had been heard in a televised Doctor Who (2005) story. At the time of broadcast, however, little attention was paid to this; instead, the episode attracted criticism for van Statten's use of the word "spoon" in a possibly sexual context. However, it was not the first use of a curse word across Who.
Van Statten orders the guards to not fire on the Dalek because it is unique despite the fact that it is killing them. Harrison Chase does the same thing in "The Seeds of Doom", ordering guards not to fire on the Krynoid, even though it is killing them, because it is unique.
Before the broadcast, media watchdog organisation Mediawatch-uk complained about certain elements of the episode, characterising Van Statten's chaining and invasive scan of the Doctor as a "sado-masochistic" torture scene. Mediawatch also objected to Van Statten's invitation to Adam and Rose to "canoodle or spoon, or whatever you British do" as inappropriate sexual language.