** The depiction of the effects of time dilation is fairly accurate, barring a few fantastical aspects. In particular, because light is more diluted at higher time-speeds, the environment becomes darker. Moreover, because the subject is moving at a considerable percentage of lightspeed (especially by the standards of the Disc), everything in front is blueshifted. There is a HandWave thrown in about ghostly versions of light and sound, though, to explain why time-slicers are still able to converse.
** The brief note on the awful quality of native Ankh-Morporkian chocolate is a subtle reference to very real history of similar food adultery and lackluster quality control in British history. Cocoa powder for drinking and for chocolate, during the 1800s and 1900s, was ''routinely'' being cut with, among other things, brick dust, red lead, iron filings, and vermilion. Even in the modern era, British attitudes towards chocolate quality are far less stringent than, say, German or Swedish ones. The British-designed Mars Bar, for example, is routinely known amongst chocolate makers as "the rubbish bar", as standard practice for the nougat center is to make it by melting down and recasting all of the nougat that ordinarily would have been thrown out due to being too substandard to sell on its own.
* StrangledByTheRedString: At the end, Susan Sto Helit and [[spoiler: Lobsang Ludd]] begin to talk as though they have mutual feelings for each other, and (it's implied) begin a romantic relationship. However, there has been nothing vaguely romantic in their interactions up to that point — which is odd, because there was a blossoming awkward romance between Jeremy and Myria/[[spoiler: Unity]], and Susan was quite taken with the idea of "someone like her" throughout the book. Obviously Sir Terry had a romance in mind from the start, but didn't put in any kind of hints when the two actually met face to face.
* UncannyValley: Lady [=LeJean=] looks impossibly beautiful (being an idealization of the most beautiful image of a woman ever made on the Disc). If that isn't enough to put her solidly in the Valley, because she's basically a MeatPuppet for something that has no understanding of human existence, she moves wrong at all levels. Instead of her face moving from expression to expression, is sort of goes from expression to expression without her features going through the intermediate stages. However, with her CharacterDevelopment, it's almost certain she gets over this as time goes by.
** Much more the case with the other embodied Auditors, who build blandly-nondescript bodies but can't ''move'' in them naturally like real humans.