Russell T. Davies contemplated devoting a two-part slot to an Ood adventure, but ultimately decided that the storyline would work better if it was not overcomplicated.
Ida Scott from The Impossible Planet (2006)/The Satan Pit (2006) was going to be a main character. She would now be a member of an investigative team looking into conditions on the Ood-Sphere, who would be dismayed to discover that her estranged father is now involved with Ood Operations - although it would later be revealed that he is secretly acting on behalf of the Ood.
An extended sequence set in caves beneath the planet's surface, in which The Doctor searches for the giant Ood brain, was cut for time.
Russell T. Davies noted during production of the Ood's introductory episodes that he considered their home world to be close to that of the Sensorites - hence the mention of the Sense-Sphere.