The Christmas Invasion - S2-E2
Character mistake: When Llewellyn is describing what was carried onboard Guinevere One, the UNIT computer displays the space probe's name misspelled "Guinivere" One. (00:26:50)
Character mistake: When the Doctor and Rose are walking back to the TARDIS at the end, he explains to her that Queen Victoria was hemophiliac. She wasn't. She was a carrier of the disease due to a mutation in one of her parents' reproductive cells (probably her father, Edward, Duke of Kent, because he was in his fifties when Victoria was born), but since she only had it in one of her X chromosomes, she didn't actually suffer from it as the gene for it is recessive, which is why most hemophiliacs are male. It is true that several of her children inherited the gene, and one of her sons was hemophiliac, but not Victoria herself. (00:40:55)
Character mistake: The Doctor gets excited about the major events of 1953 and mentions that everything was "off the ration" (that is, the food rationing put in place in the UK during the Second World War had ended). Rationing actually ended the following year. (00:05:55)
Character mistake: Dr Singh refers to "a single protozoa." "Protozoa" is the plural form. He ought to have said "a single protozoan." (00:08:05)
Character mistake: In an early scene with Yvonne Hartman, she says "We've just measured the ghosts' energy at 5000 gigawatts." There are at least two mistakes here: (1) watts are a unit of power, not of energy (that would be joules); (2) later on, when Hartman is showing the Magnaclamp to the Doctor, she refers to imperial tons and says "Torchwood refuses to go metric", but a gigawatt is a metric unit.
Chosen answer: The Master knows that deep down, he deserves death for the crimes that he's committed throughout his life, and since he regards The Doctor as his arch-foe, he expects it to be at his hands. The fact that The Doctor is still willing to forgive him for all of his crimes hurts him more deeply than death would.
Captain Defenestrator