Hyperspace Is a Scary Place: It’s not so much hyperspace in the SFnal sense as the Void Between the Worlds, but the primordial chaos/cacoastrum of the bulk/plenum is, by and large, not a very scary place, because it invariably kills you before you have the opportunity to be scared. Its adjacentia, however, if anyone ever should manage to punch a hole in the universe, would almost certainly be utterly terrifying – the more so the more you understand about them.
(Well, okay, technically it doesn’t, but that’s because there’s no time outside the universe for there to be any instants of. But the effects of cacoastric exposure – to wit, dissolution/transformation into slightly less primordial chaos, with cake – amount to much the same thing, even if they happen at sausage squared over blue hadron teapot.)
Human Weapon: In some ways (and inserting obligatory not-human disclaimer), many members of the sentinel daressef would count, what with the various military-basic upgrades and then the possibility of various special upgrades on top of those. On the other hand, strongly averted because the Imperials are smart enough to treat weapons that are people as people first, in much the same way as they manage to avoid the AI revolution.
Humans Are Smelly: If there were any around, they would be.
But it’s hardly unique to them. All primitive species are: because it’s a consequence of advanced species (and especially those who take their cue from our friendly local aesthetes) investing in both much improved senses of smell plus excellent personal hygiene via biotechnology and nanotechnology. By the time you have skin that dirt literally won’t stick to, sweat that smells of roses and avoids supporting bacterial growth, and even shit that literally doesn’t stink… well, everyone not comparably enhanced is a stinky ape.
Or stinky lizard, stinky slime mold, stinky bunch of tentacles, whatever.
It is, however, considered polite not to point this out. It’s no sin to be primitive. Now, if it’s by choice, on the other hand…
Huge Holographic Head: Mostly averted, because while a perfectly trivial piece of image manipulation, even the usual suspects have long since figured out that it’s really hard to be taken seriously by people you’ve invited to stare right up your Huge Holographic Nostrils.
House Fey: While obviously not true in a literal sense, given the prevalence of AI house brains capable of self-development, houses tend to develop a fair bit of personality over time. And so, talking to the intelligence of a smart house with a few centuries or millennia of run-time under its belt can, on occasion, seem quite like dealing with a rather eccentric domovoi.
Hologram Projection Imperfection: As mentioned under the Hologram trope, their glamor failure is deliberate; trigraphic projections are splendidly perfect and accurate, and even can dynamically correct for lighting differences when used sender to receiver – so, unless otherwise called for, they’re deliberately tuned to slight transparency to clue people in that they aren’t solid objects.
NOTE: These are TROPES and or Fantasy Counterpart Culture ANALOGIES. No real cultures were harmed in the making of this fiction.
Hobos: Some individually-wandering members of the Traveling Houses (for more on which see Romani); while generally better off and by no means living a wealth-free life, even back in the day, some other aspects of the lifestyle and reason why one might take it up are similar.
Romani: The Traveling Houses do have some cultural elements in common with the traditional Fantasy Counterpart Culture – a nomadic lifestyle, for one, starting with caravans – although also barges and later, starships – but also have their differences. They’re not known/stereotyped for fortune-telling, for example, and are known for delivering the law (in the shape of wandering deemsters), education (in the shape of traveling teachers and new books), exotic speculative trade goods, and in some cases, the mail. And some members wander individually (hence the reference from Hobos).
And, of course, the Empire’s culture is much worse at sustaining wacky prejudices against people and altcultures who/which prefer to wander than to settle.
High Times Future: As long as you’re competent to do what you have to do, when you have to do it, your neurological state and how you got there is your own business. Download all the drugs you like! (Well, except those falling under the category of Coercive Substances, or those which drive you insane in ways likely to cause harm to others: magical berserker nutball powder is off the table. But apart from those it’s between you and your mind.)
High-Tech Hexagons: Well, yes, for reasons of efficiency and domes and carbon and geodesic construction and other practical reasons given in the trope page.
Plus, of course, six-sides shapes are only natural for people who count in twelves.
Here There Be Dragons: Seen on star charts which include the Resplendent Exponential Vector system, and in particular, that moon given over to the biogenesis project working on creating the mythologae the way they really ought to have been.
(They haven’t managed to actually create any dragons yet, but no-one wants to be caught by surprise when they do.)
Great Big Library of Everything: The Empire’s Repository of All Knowledge, which is exactly what it says on the tin. Apart from containing copies of every work in every medium published anywhere in the Empire and many of the unpublished ones too, it routinely sends out collections agents to make sure it has a copy of any work it can get its hands on anywhere else within its light-cone, too. (Such agents can be quite persistent. The Black Chamber does not like to take no for an answer.)
God Test: Have gone rather out of fashion since most examples of a miracle became something people could purchase at their local hardware store, leaving things people could ask to be done as proof of divine bona fides too academic (“Violate conservation of energy!”), too insane (“So make a rock too heavy for you to lift, then lift it anyway!”), or impractically large (“Go ahead then, CREATE A UNIVERSE.”).
A Glitch in the Matrix: Avoiding this sort of thing, when it comes to virtual reality, is one of the few legitimate uses for the Out-of-Mind visual textures. (Others mostly including hiding gifts and playing really terrible practical jokes.)
A more commonly seen variant are “weavespiders”, small metallic fractal spiders (which everyone knows to ignore) used in virtual realms to collect trash, reassemble broken scenery, and otherwise do maintenance. While, obviously enough, this can simply be done programmatically without requiring any visual metaphor, reifying them like this is a simple way of avoiding the uncanny valley effect of changes “just happening” with no apparent in-world cause.
Giving Radio to the Romans: Tends to happen quite a bit, given the lack of any Prime Directive-equivalent and the large number of free traders around who are more than happy to sell anything to anyone who can pay – and that’s not even counting the “fell off the back of a starship, guv, ten bob to you for cash” crowd – and the desires of most people on most worlds for shiny toys.
Some of the real life consequences mentioned are prevented by the Empire’s also having a bunch of private organizations of various kinds, including professional civilization-uplift consultants, who go around helping people not to be total screwups under these sorts of circumstances… but not all of them. But, y’know, free will and all, and it’s not as if they made you invest in technologies granting you the capacity to be total dicks and then use it in that exact manner, belike. That’s on you.
Geometric Magic: Well, not magic, no. But a lot of the Flamic rites and rituals make use of sacred geometry, as reflecting the perfect order of the conceptual universe. Elmiríën, in particular, as eikone of order, structure, stability, perfection, and proper functioning is very fond of these, to the point of self-representing as a perfect orrery of Platonic solids.
Also, there’s a lot of geometric engineering.
Genius Breeding Act: Averted, despite the tremendous respect for intelligence – as you might expect from the civilization that considers Arranged Marriages an unpleasant subclass of slavery. (Which, as I said back then, doesn’t mean that friends and relatives aren’t happy to engage in generous quantities of Shipper on Deck…)
…actually, more inverted, in a sense. The Reproductive Statutes do do the opposite, since while fully recognizing the rights, etc., of those with hereditary disabilities, since ethics is time-directional, that does not extend to deliberately or negligently creating more of them, respecting the right of the potential sophont to be well-created. And for a sufficiently advanced society, “hereditary disabilities” includes “functional amentia” to a degree that goes a long way farther than anything anyone in our history would have classed as even mild intellectual disability or other related conditions.
So if your genes aren’t up to scratch in this area, no reproduction for you! That’d be felony dysgenesis.
Gem Heart: Truth in television where silicon-based or carbosilicate lifeforms are concerned, although while some make use of gem-like structures (say, the galari, who even look like cut gems due to their crystalline structure) one is equally, or even more likely, to find Rock Heart. Or plain old crystalplasm.
Otherwise, mostly seen as things like the trope-page-mentioned gizzard stones.
The Game Come To Life: Doesn’t happen literally, but perhaps a little played with inasmuch as there are augmentality games – designed to integrate seamlessly with the real world and make use of real-world elements during gameplay – which blur the boundary more than a little. (Enough so that a number of them have been manipulated by various sponsoring entities to achieve real-world goals. Amazing what people will do for progress towards an achievement…)
And then, of course, there was the Lord Blackfall incident.
Galactic Superpower: Somewhat true, in the “United Nations” sense, since the Accord of Galactic Polities doesn’t actually wield all that much power over the Associated Worlds, but the Associated Worlds do make up the majority of the setting. (Less so in numbers, given the presence of the 4/5ths as large Voniensa Republic, but more so in terms of attention paid and interesting things happening.) Averted, however, inasmuch as the Empire is a mere few hundred systems among ten-thousand, even if they are the largest polity of the Worlds and one that punches well above its weight militarily, economically, and culturally.
Gaia’s Vengeance: One of the worlds the trikhad invaded and attempted to strip-industrialize during their brief conquistador period was Fynfil (Tanion Wilds), with its highly complex, highly interlinked, universally mutualist ecosystem. To say it went very badly indeed would be something of an understatement, because there’s not a lot you can do when pretty much every lifeform on the planet is willing to cooperate in killing you. Indeed, when pretty much the entire ecology is dedicated to the war effort.
And the word went forth: fuck not with the myriasoma.