Roots: 24 (the title). The film Sunshine. Planet of Evil. Cyclops from the X-Men. There are references to Elvis Presley and the Beatles.
Goofs: If the Doctor can turn Martha's phone into a superphone like Rose's with the sonic screwdriver, why did he need to replace parts when he upgraded Rose's phone in The End of the World?
So what exactly does it mean to "crash into the sun", when stars don't have a solid surface?
The computer announces the time to impact at somewhat irregular intervals. Also, the time it took for the cast to move around the ship seemed to vary considerably between conveniently quickly or conveniently slowly according to plot requirements.
How does the oxygen in the infected peoples' bodies get changed into hydrogen? That kind of nuclear fusion would require a colossal amount of energy, and leave the bodies a lot hotter than 100 degrees, and would create a lot of neutron radiation. Furthermore, it would lead to the bodies literally falling apart at a molecular level.
Why is the light from the infected peoples' eyes not visible through their eyelids? And given that they seem to be able to see where they're going with their eyes closed, why do they need the masks with the visors? [Perhaps the suits prevent the possessed bodies from burning up too quickly.]
Why does the screen for the escape pod jump from "Jettison Reactivated" to "Jettison Initiated".
Why are the controls to remagnetise the escape pod on the outside of the ship?
Why don't the bodies incinerate instantaneously that close to the sun?
If releasing the material taken from the star solves the problem, then why doesn't the star just do that in the first place? And how, exactly, does it prevent the heat shields from collapsing?
Technobabble: Endothermic vaporisation [whilst this term is technically correct, vaporisation is an endothermic process anyway].
Continuity: The Doctor upgrades Martha's phone into a phone anywhere in time and space phone by using the sonic screwdriver. Martha's mum has people working for Mr Saxon in her home, who are monitoring her phone calls and want either information on the Doctor or to get hold of Martha. She has voted, but refuses to tell Mr Saxon's associates who she voted for.
The Doctor has fillings in his teeth.
The star is alive. When its "heart" has been scooped out it can possess human beings. When it does this, it changes people's internals - their body temperature rises to 100 degrees, and the oxygen in their body is replaced by hydrogen.
The ship is a cargo ship that's entirely automated, but has seven crew members. It may be called the SS Pentallion. [One of the security questions relates to when the SS Pentallion took its maiden voyage, but it is not explicitly confirmed that this is the name of the ship.]
Kur-Ha has mineral lakes on which you can ice-skate.
Links: Deadlock seals (School Reunion) are mentioned again.
Extras: This story has an episode of Doctor Who Confidential. The BBC website had an online commentary, which has since been taken down. It also has a behind the scenes video podcast.
Location: The Toragy system, half a universe away from Earth, presumably far in the future; Earth after The Lazarus Experiment and on election day.
Future History: Energy scoops for fusion are outlawed by this time period.
The Bottom Line: 'Burn with me.' This is a fast-paced action piece with a few character moments thrown in for good measure. There's not much substance beneath this, however, and the overall verdict must be that this is a thoroughly disposable episode.