Planet of the Ood
Roots: Spartacus, Toy Story (the claw).
There are references to Ferrarri, the Simpsons, the rough guide series, West Ham FC, Persil, and foot-and-mouth.
Goofs: The Doctor comments on the impossibility of a species evolving as slaves but not on the impossibility of them evolving with brains that have to be held in their hands.
It's extremely odd that the Doctor and Donna are so concerned about slavery here but didn't even comment on it when they were in Pompeii in the previous episode.
How does Donna know that red eyes are a sign of trouble when she's in the crate?
The claw device should have four arms, rather than three, if it is designed to move rectangular crates.
If the Ood's external brain processes memories, how are the processed Ood able to remember their orders?
If there's no alcohol permitted on Ood-Sphere how are the buyers able to enjoy a free bar?
So all those timed explosives are able to be switched off by deactivating just one of them?
What is Ood Sigma thanking the Doctor for? Nothing he did made any difference to events.
Continuity: The Doctor carries a stethoscope.
Donna learned to whistle at West Ham matches, which she attended every Saturday. She was born in Chiswick.
The Ood have a telepathic song. Natural-born Ood have secondary hind-brains connected to their head by a long chord. These process emotions and memory, whilst there is a massive third brain which survives as an independent entity. It telepathically connects all of the Ood.
Links: The Ood previously appeared in The Impossible Planet/The Satan Pit. The Doctor mentions the planet Sense-Sphere (The Sensorites) being nearby.
Extras: This episode had an episode of Doctor Who Confidential.
Location: Ood-Sphere, 4126.
Future History: Tri-galactic appears to be a broadcast network. The currency of this era is credits. This is the era of the Second Great and Bountiful Human Empire, which stretches across three galaxies.
The Bottom Line: 'They're slaves.' A solid episode, although having an episode about the evils of slavery right after an episode set in ancient Rome is somewhat tone deaf.