Sound effects matching the door opening and closing sounds from Doom (1993) are occasionally used (especially noticeable when Toby goes searching for the "voices" distracting him from his archaeological findings).
The simple name of the Ood was an intentional contrast to Russell T. Davies' typical flair for ostentatious alien monikers.
This is the first episode of the revived series to use a quarry as an alien planet - quarries were frequently used in this manner in the original Doctor Who (1963). Russell T. Davies was not a fan of this production decision.
Originally, the Slitheen were going to be in this episode. or, more specifically, another family from the planet Raxacoricofallapatorius - with the idea being that they had become enslaved by humanity. The Raxacoricofallapatorians secretly believed that the planet being explored was actually the dwelling place of their god, who would free them from servitude. However, Russell T. Davies ultimately became concerned that the presence of the returning monsters was detracting from the humans whose pioneer spirit he felt was at the heart of the tale.
First appearance of the servant-bred species, the Ood.