Alternative Character Interpretation: Reacher Gilt's death in the epilogue. Did he blindly walk out of the room, or did he willingly choose death over serving Vetinari?
Genius Bonus: The 'Agatean Wall' Vetinari and Slant reference when the bankers are meeting the Patrician is not only a real thing but is basically exactly what Slant described. In real life, when somebody on Wall Street is given knowledge of an upcoming deal — for instance, a merger between two companies — that will affect a stock's price, they are said to have gone 'over the Great Wall' and are henceforth forbidden from commenting or acting on that information. Of course, in our world, insider trading and such is generally... not looked highly upon, but at the heart of it they do just agree not to do it.
One of the parts of the Clacks tower mechanism is a "Jacquard", which is known to jam. As it turns out, a Jacquard mechanism is a mechanical punch-card reader for controlling a loom. So it makes sense that it can send a prerecorded distress call, among other things.
Reacher Gilt's plan is, word-for-word, exactly the type of scheme that Mitt Romney was accused of doing repeatedly as part of Bain Capital during the 2012 US presidential election.
The telecommunications industry has only sunken deeper into the pitfalls this book described since it came out: a few greedy corporate interests who never understood them in the first place buying the provider companies out from the bright passionate men who made them and running them into the ground, charging higher and higher prices for worse service with frequent breakdowns and interruptions and holding on through practical or actual monopolies so that customers can't take their custom elsewhere. However, unlike in the novel, where government policies root out corruption and create healthy competition, in real life these companies have instead bribed and bullied governments into doing their bidding, freezing technology and supporting rather than undermining their poorly-run monopolies.
Heartwarming in Hindsight: "A man isn't dead as long as his name is still spoken" became even more powerful and moving following Pratchett's demise, with many of his fans doing exactly the same as the clack employees by making his name circulate on the web.
Memetic Mutation: The clacks code GNU. G instructs that the message be sent to the next tower, N means not logged, and U instructs that the message be returned when it hits the end of the line, resulting in an invisible message being perpetually sent up and down the clacks. When Terry Pratchett passed away in 2015, Discworld fans did not say RIP but GNU, with the phrase "GNU Terry Pratchett" being repeated on social media and even put into the background code of websites and servers so his name will always be spoken.
Woolseyism: In the Finnish translation, Reacher's claim that the Grand Trunk is "about people" (a phrase that doesn't really exist in Finnish) is rendered as him saying that the company "connects people". Not only does this work as an example of a similarly meaningless marketing phrase, it also references the slogan of Nokia, which used to dominate both the global cell phone market and the Finnish economy around the time that the novel was written.
The film:
Broken Base: A mild one. Among Discworld fans, there are those who like the adaption for what it is, a Broad Strokes adaption of a book with top-notch casting, with plenty of on-screen chemistry about. The other half, while acknowledging these traits, is still not impressed due to the massive changes to the story (The curse of the post office is something completely different in the books), and generally making Moist a much worse human being (with higher "body count" to boot) than he actually is; he is constantly scheming to get away, when in the books he's doing a two-pronged approach (planning his escape and actually helping along the post office) even in the beginning, and later more genuinely becomes a good guy due to his dislike of Gilt. It also completely defangs Gilt, making him a straight unscrupulous businessman instead of Moist at his worst writ large.
Reacher Gilt is the corrupt head of the Grand Trunk after the Dearhearts are bankrupted, running it into the ground to line his own pockets. Having multiple Postmasters and the uncovered spy John Dearheart assassinated by Mr Gryle, Gilt half-heartedly attempts to dissuade Moist von Lipwig from restoring the defunct Ankh-Morpork Post Office and then orders Gryle to burn the office down and kill Moist and his staff when this fails. As the rivalry between Trunk and Post Office heats up, Gilt slowly loses his grip on sanity, beating his chief accountant Horsefry to death for keeping records too meticulously and threatening to drop employees to their deaths when wrongly suspecting them of sabotage, not caring when his chief engineer Mr Pony protests that the employee is his niece and later threatening her if the Clacks loses its race with the Post Office. When seeming to have won, Gilt tries to speed up Moist's scheduled demise, and when finally exposed as a criminal, spitefully smashes an omniscope, uncaring of the potential harm to everyone and almost causing Moist to be hanged.
Mr Gryle is a Banshee and sadistic assassin working for Gilt, proudly describing himself as "the Post Office curse". Having killed the four Postmasters before Moist von Lipwig in ways mistaken for gruesome accidents, Gryle also murders John Dearheart, Adora Bella's brother, just after sarcastically announcing his presence, and mocking him before detaching his safety harness and letting him fall to his death. Later told by Gilt that Moist is a "nuisance", Gryle burns down the Post Office—nearly suffocating Tolliver Groat—and attempts to savagely kill Stanley while bragging about eating his own grandmother. Finally confronting Moist when he attempts to rescue Stanley from the blaze, Gryle gleefully confesses to his previous murders—uncaring that this gives Gilt away—and brags that John "squealed like a pig" as he tries to complete his "collection" of Postmasters by ending Moist's life.
Narm: Because of Moist's criminal past Adora Belle started smoking. This is given the same dramatic heft as the other ways in which his schemes ruined the lives of other via ripple-effect.
Literally everything Mr. Gryle says in his final scene. His taunts related to post are painful, and he's such a Large Ham that it's impossible to take him seriously.
Questionable Casting: Richard Coyle's face is far too distinctive to be generic like Moist's.
. The Agatean Empire being, of course, the Diskworld equivalent of Imperial China.