Scifi Writers Have No Sense Of Scale - Television Tropes & Idioms

"Space. It seems to go on and on forever. But then you get to the end and a gorilla starts throwing barrels at you."

-Fry, Futurama

Space is big. Really big. You just won't believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it's a long way down the road to the chemist, but that's just peanuts to space, listen...

-The Guide, The Hitch Hikers Guide To The Galaxy

Dr. James Van Allen (the Van Allen Radiation Belt around the Earth is named after him) was once asked by a reporter to 'define space.' He replied, "Space is the hole that we are in."

Most people can't get their minds around just how big the universe is. So it should come as no surprise that most Speculative Fiction writers can't either. This is chiefly true of creators of TV, film, and video game SF. Creators of written science fiction can be positively obsessive about accuracy. On the other hand, sometimes not. This is, by the way, a popular way to distinguish good print science fiction from bad print science fiction. And it's why a lot of science fiction fans don't like the movie and TV adaptations of their favorite books and stories. The usual blend of Adaptation Decay and Did Not Do The Research is a surefire way to leave the adaptation with no sense of scale.

As an example, consider that a light year is about ten quadrillion metres (for Yanks: nearly six trillion miles!). That's ten-to-the-power-sixteen metres, or ten petametres. At the opposite end, an atomic nucleus is on the order of a quadrillionth of a metre. That's ten-to-the-power-negative-fifteen of a metre, or a femtometre. Such outrageous SI prefixes

rarely appear in fiction, and that's before we get anywhere near the scales of galaxies and subatomic particles. If it sounds like a number made up by a child (yottametres, septillion seconds), the writer might have actually taken it seriously.

Distance: Whenever you hear terms like "millions of miles", "sector", "quadrant", "parsec", or "light-years" (assuming the writer isn't so misinformed (or stupid) that he thinks it's a unit of time), just read it as "a honkin' long way". The writers often have no idea just how far apart things are. If it's "micro-" or "nano-", just read "mighty small".

Examples:

In Star Trek The Original Series, the Enterprise was frequently "the only ship in the quadrant", which apparently meant something very different back then.
- They also travelled to the edge of the Galaxy, and in the Wall Banger film Star Trek V, to the core of the Galaxy.
It's possible to go too far in the other direction, as well: All Our Yesterdays refers to Vulcan as being millions of light-years away. The entire galaxy is about 100,000 light-years across at its widest point.
In the Star Trek Voyager episode "The Fight", Voyager encounters a Negative Space Wedgie that is "2 light years across". They start "11,000 km" away from it and yet, the whole phenomenon is visible on the viewscreen. As the Agony Booth review of this episode points out, this is exactly like "putting your nose on the ground, and still being able to see the whole landscape from horizon to horizon" except...you know...even worse. The thing also looks about as big as Voyager when it engulfs it, which might make slightly more sense (for a given value of "sense") since Voyager is apparently the size of a planet◊.
- Oh, there's one just as bad in Enterprise. I know, people are shocked. It comes when describing the Expanse, the mysterious spacy-cloudy-thingie that the Xindi are hiding in. It's said, on screen, that it spans 2000 light years, and is 60 light years from Earth. Simple trigonometry shows this thing, seen from Earth, would therefore occupy 179.9 degrees of the night sky (out of 180) at least part of the year. Apparently, we just didn't you know, notice that HALF THE FREAKING SKY was missing a lot of stars.
- The problem may come from the way the scripts are written. Star Trek scripts often start out with units and technology names left blank to be filled in later. The initial version of the script will actually be written like "We can traverse the [really big distance] to Xffto Seven using [insert technology here]." Since the people who fill in the blanks may not know or care whether the really big distance involved is interplanetary or intergalactic, they're likely to just make up a big number and attach a big unit of distance.
Blakes Seven uses "galaxy" and "solar system" interchangeably.
- Despite travelling from Earth to the edges of the galaxy and back, there was part of the galaxy it would take them centuries to travel across. Earth is relatively close to the edge of the galaxy, however.
Babylon 5 quotes distances of tens of light years between the major powers, but later shows a galactic map on which the major powers control most of the galaxy, requiring distances to be roughly a thousand times greater. In another example, at one point a ship that has been supposedly lost deep in Hyperspace is reached by a chain of less than twenty fighters with only one thousand kilometres between each of them, meaning that the supposedly distant ship is less than 20000 km from the jumpgate. This can be handwaved by saying "Well, it's Hyperspace", but...
- J. Michael Straczynski acknowledged the problem of space's true scale when talking about showing space battles on TV, pointing out that TV viewers want and need to see the ships in the same screenshot pounding away at one another, but that any actual kind of space battle would likely take place at distances far too extreme for this (thousands of kilometres at minimum). The battle between the Shadows and the Narns in "The Long Twilight Struggle" attempted to acknowledge this on the screen; most of the fight consists of the ships simply accelerating towards one another, and only the last (catastrophic) few seconds includes any visual proximity. Nonetheless, most of the series' remaining battles gave in to the Rule Of Cool anyway.
The moon in Space 1999 was variably described as being billions of kilometres, miles, and light-years from Earth, resulting in roughly equal difficulty in returning despite the fact that the first case would put the moon closer to Earth than Saturn, while in the latter case the moon would be vastly more distant from the Milky Way galaxy than the Great Wall, currently the largest known feature of the universe. It (the moon) passed between star systems at speeds fast enough that the passengers went through a star system per week, yet remained close enough to each and slow enough to reach a planet via shuttle for days at a time.
Probably the most spectacular example is in the first segment of the Doctor Who story "The Trial of a Timelord", where Earth was apparently hidden by moving its entire solar system several million miles, which is the celestial equivalent of hiding from your date in an empty movie theater by leaning an inch to the left. For scale, Mercury never comes within 28 million miles of our Sun, despite being its closest planet.
- In "The Wheel in Space" the Cybermen divert a meteor storm in the direction of the titular space station by sending a star nova in the Hercules Globular Cluster, which is 25,100 light years away. The disparity in scale is at least 12 orders of magnitude.
The radio show Planet Man referred to the Astro Drive, which would enable the hero to travel the "millions of light-years to Alpha Centauri". Alpha Centauri is just 4.37 light-years away - in fact, it's the closest star system to our own. Actually traveling "millions of light-years" would be a lot more impressive.
The original Battlestar Galactica invented their own units of distance based on standard prefixes, so you'd have centons, microns, etc. However, the writers never realized that "micron" is an existing unit of distance, so you'd have ships that are ten microns apart when in reality that means they are separated by tiny fractions of an inch. These got confused to the point that centons were also used as units of time.
Freelancer messes with distance so much that it's not even funny. Planets are two kilometers wide. Moving at three hundred meters per second was considered fast. Moving between planets took barely more than fifteen seconds. Moving from one side of the entire galaxy to the other barely took more than an hour. Asteroids are barely larger than a car. Moons are barely larger than a battleship. The examples are countless.
Any show where someone mines space. While minefields make sense in 2D, trying to mine a 3D area is a lot harder, and trying to mine a 3D area on astronomical scales is simply idiotic. Blake's 7 showed someone mining the Milky Way galaxy to keep out aliens. This is simply impossible. By the time you gathered enough matter to build this minefield, there'd be no Milky Way galaxy left. Similarly, a Deep Space 9 episode featured a mine field around a solar system. While this is much more plausible (in the way that swimming across the Atlantic is more plausible than swimming the Pacific), they did it in a 2D plane, so that anyone trying to avoid this minefield could simply fly over or under it. Even then, they were building it at a rate that would have taken them hundreds of years to complete (if anyone had done the math). DS 9 later averted this, with a space minefield around a very small area (the opening of a wormhole) with a realistically long time spent laying it. (or rather, using matter replicators to let it lay itself - but that just gets into Energy usage, below.)
- The difficulties in preventing movement in 3D space is spoofed in an episode of Futurama; environmental protesters are attempting to stop an tanker full of dark matter by forming a human circle around it. Unfortunately, they forgot that objects in space aren't limited to moving 'forwards' and 'backwards' - the tanker merely scoots upwards a few metres and merrily flies over their heads.
- In a similar vein, an episode of Star Trek The Next Generation had a "Dyson Sphere": a huge sphere built around a star with a radius approximately the same as Earth's distance from the Sun. This troper never understood where the architects found that much material. Or why they abandoned the sphere just because the star was dying. I mean, if they can build it, they can also move it.
  - A Dyson Sphere[1] is made from the (former) planets of that solar system. And no, it (at least the Shell version shown) can't be moved. However, the one in that episode was said to be made of neutronium, the hyperdense collapsed matter in the heart of a neutron star. Meaning it would not only far outmass the star it surrounded, but would collapse and explode at the same time without some means of maintaining the strongest pressure physics can allow. I guess Sci Fi Writers Have No Sense Of Physics, either.
- One way writers attempt to justify their 'space minefield' is to use mines with a very long engagement range, such as an X-ray laser that uses a nuclear explosion to create a big focused blast of energy headed towards the target. That way, the mines can still threaten your ship even though they're hundreds of kilometers apart and spread out all around a planet.
- In the case of DS 9 they were specifically mining the exit to a wormhole, the exit was a 2D plane. The wormhole existed as a highly convienent choke point (It's other end was impractically far from Federation space). While the wormholes diameter is not small, placing a few layers of mines right in front of the exit would ruin the day of anyone exiting the wormhole. The mines being self-replicating however...
No so much a problem of distance as of volume, but the movie Starship Troopers has starships flying so close together (while in orbit!) that one of them crashes into another when shot. Space is big, there's plenty of room. If you're flying within visual distance of another ship and you're not trying to fight them or dock with them, something is wrong.
- Trying to fight with them would be better at a distance, unless they can't fight back.
The game 7 Days a Skeptic revolves around an old locker discovered floating in another galaxy by an exploration ship. Ignoring the staggering improbability of finding anything that size in an entire galaxy, the locker was launched from Earth four hundred years before the game starts, in the modern day. The Andromeda Galaxy, our galaxy's closest neighbor, is 2,500,000 light years away. This simple metal box would have had to travel at multiple times the speed of light to make it out of the Milky Way in such a short time.
- Actually, the closest known neighbor to the Milky Way is the Canis Major Dwarf Galaxy. The locker would still have had to travel some 62.5 times the speed of light in to get there though, so I guess I'm only quibbling.
Averted via Rule Of Cool in Tengen Toppa Gurren Lagann which features such gems as galaxy-sized mecha hurling spiral galaxies as shuriken. They were in an alternate reality, but even before that giant mecha the size of the moon were laying the beatdown on slightly smaller mecha using missiles the size of cities. Good thing it was so awesome.
The video game EVE Online subverts this one admirably. Distances in solar systems are realistic - from any particular planet, all other planets seem like points, and are several AUs away. FTL technology is required to get anywhere. There are even two types of FTL: short range warp drives which are used to travel within systems (fitted to ships), and long range star gates for travelling light years between star systems. Combat is frequently with ships that are only visible by their targeting icon.
- Interestingly, they also point out the sheer size inherent in a single system. The game's equivalent of dungeons and hideouts are not actually hidden, per se. It's just that there is no concievable way to locate them without having the specific co-ordinates. Complexes are reached by short-range intra-stellar hoppers, which jump you into the location. Of course, why a society with casual FTL drive lacks halfway decent sensor ranges is a mystery.
The Five Star Stories has a similar problem to Blakes' Seven. The titular Five Stars are most commonly referred to as "The Joker Star Cluster", even though real clusters have several thousand stars, but it's also referred to as The Joker Galaxy, which is even worse & The Joker Constellation, which doesn't make sense either, since constellations are only called as such by people who can see them from a distance. It could possibly be a star cluster if the Five Stars are just the only ones with planets out of a cluster of thousands, which is plausible, if not very likely. It could also be a multiple star system of five stars orbiting a common centre of mass. Either way, Mamoru Nagano really needs to study up on his astronomy.
Surprisingly, no one has referenced the wonderful aversion of the issue of distance in David Weber's Honorverse. The scale is frequently referred to, usually by use of the phrse "on which God built solar systems" and occampanied by the fact that yes, we are two hundred million miles apart at the moment and we aren't going to be in weapons range for many hours.

Time: Time consists of "Now", "A very long time ago", "A few years from now", "A very long time from now", and "Next Tuesday". There's an exception for specific points in documented Earth history, but only to break out period costumes or do a plot about changing history. Writers in the 1950s and 1960s thought that placing something in "The Year 2000" was as good as placing it a million years in the future. Even today, The Future is generally only 300-500 years hence, even if we've developed a vast star-faring civilization. Some of this is a product of the progress-mania of the early 20th century - after all, if in your lifetime, you'd seen mankind go from inventing the airplane to walking on the moon, it didn't seem all that unreasonable that we'd be living on Jupiter by 1999. This sort of thing gives many shows set Twenty Minutes Into The Future a shelf-life of about fifteen minutes.

Examples:

Doctor Who, particularly during the Patrick Troughton era, dated an awful lot of its high-tech future stories to the twenty-first century. Going in the opposite direction, the story "Doctor Who and the Silurians" named a species after the era a million years before they were around. Someone caught this too late, and in their next appearance, the Doctor pointed out that their name was a misnomer.
- The series's first story, about cavemen, had dates slapped on it in different draft scripts ranging from 1000 BC to 1,000,000 BC, with no apparent thought that these were different in any way. Similarly, "The Daleks' Masterplan" had dates from 5000 AD to 1,000,000 AD in different drafts.
Space 1999 had an advanced base on the moon in the year of its title.
Power Rangers has shown the year 2025 to be more advanced than the year 3000, and once traveled back to show Salemesque witch hunts in 18th century English-colonized California.
The "present" in Quantum Leap is 1999, and featured self-driving cars (and time-travelling scientists) amongst other things. However, the show all but declared that its native timeline and ours weren't the same (though they were apparently growing closer all the time).
Video game example: The original Mega Man series, set in 200X, includes 4-foot-tall robots equipped with fully-developed artificial intelligence, superhuman speed, reflexes, and fighting ability, and weapons involving plasma cannons, lasers, time manipulation, and holograms. Comparatively, Honda Motor Company's ASIMO robot can't even make it up a set of stairs without falling over. They later changed it to 20XX.
Many video games in the 1980s revolved around some kind of nuclear apocalypse occuring in 1999 or 2000. Crystalis, for example (The Game Boy Color remake simply said "in the distant future".)
The "Apocalyptic Violence Anime" spoof episode of Excel Saga opens with the announcer shouting "In the year 199X!" The studio audience shouts "It's already over!" and the flustered announcer tries again with "In the year, 200X!"
Spoofed in an episode of Harvey Birdman Attorney At Law. George Jetson, after arriving in our time, treats Birdman like an inferior creature, stating proudly, "We are from the future! The far off year of 2002!". Birdman glances at his calendar, which read "March 2004".
- The Jetsons, according to The Other Wiki, was supposed to take place in 2062, but this was never mentioned in the series itself.
Parodied and subverted on Late Night with Conan O'Brien's Year 2000 sketches, where Conan O'Brien and Andy Richter would make ludicrous predictions about the year 2000 (the show began in 1993), set to dream-like music with "In the year two-thoooousaaaaaand..." repeated by a band member. Even as late as 2007, Conan and different guests continue to make predictions about what will happen in the year 2000.
Star Trek, in the episode "Space Seed", explained that Earth was wracked by world wars and conquered by genetic supermen. In the 1990s.
- Of course, the episode aired in 1967, when the previous World War had only ended a little over twenty years ago. The idea that another world war might break out some time in the next twenty or thirty years was frighteningly plausible at the time.
Scientology's space opera invokes dates hilariously far in the past - ten to the power eighty-five years is an extreme example. The universe is on the order of ten to the power ten years old. Employees have to sign a contract valid for several billion years, presumably because we're all the ghosts of aliens that got sent to volcanoes and nuked millions of years ago.
The original Dune series was set 10,000 years (human history goes back 7,000 years at present) after the Robot War known as the Butlerian Jihad, featuring an old, decadent society that had presumably been going downhill for a long time. However, when Frank Herbert's son picked up the reigns and wrote prequals set before and during said Butlerian Jihad, the prequels end with all the social orders and customs, and even the religion, of Dune already established as nearly identical to the ones in the original novel. And the reader is expected to believe that they stayed exactly the same for almost a third longer than the time between the invention of writing and the present.
- Thanks to the Bene Gesserit and others like them, the Dune universe is supposed to be stagnant technologically and other ways due to its dependence on the spice.
Neon Genesis Evangelion averts this with any civilian technology, such as Shinji listening to an SDAT player most of the time, or the phones, which were, I believe, outdated when the series was made. While there WAS an apocalypse, humanity had clearly reverted back to consumerism pretty quickly, so this troper would have thought that some features would have been improved. The computers, on the other hand, are only SLIGHTLY subhuman AI, which probably won't be happening any time soon. It pretty much evens out.

Culture: Many science fiction writers, while vividly imagining technological changes, seem to think that "the future" will consist of the culture they live in, transplanted in time. Science fiction dealing with "issues" may date more quickly than any other sort: witness the novel (not movie) Logan's Run, an hysterical ephebiphobic

screed about the horrors that would surely be visited on human society if the counterculture of the 1960s were given its head. See also Zeerust, Hollywood History, and The Great Politics Mess Up.

Examples:

Marion Zimmer Bradley's Thendara House, one of her Darkover novels, posits a galaxy-spanning "Terran Empire" of three thousand years in the future, in which men and women are treated equally in every way; but a secondary plot point is that when the central character marries, her official designation and the name on her file and her ID card is not her own name, not her given name and her husband's surname... but her husband's full name, with "Mrs." in front of it. The book was written in 1983.
Likewise, the 1953 film Project Moonbase (Recipient of the Mystery Science Theater 3000 treatment) has man landing on the moon (having set out from a space station) in 1970, whereupon the male crewman is all but ordered to marry the mission commander, as it would be socially unacceptable for an unmarried couple to be sharing a small living space for the several months before they can be relieved. More, he's promoted immediately after the wedding, since it would be silly to imagine a man being outranked by his wife. The kicker? He receives his promotion from the female US President.
Robert A Heinlein's 1950s-vintage young adult novels all take place in a kind of 21st-century 1950s - with soda fountains and hot rods and interplanetary flight and aliens.
"The Last Question" also had the Population Explosion going on for at least tens of thousands of years.
Isaac Asimov attempted to speculate on overpopulation in The Caves of Steel. In the 47th century, Earth is grossly overpopulated to the point that almost 90% of the planet must be turned over to full-scale agriculture, with its population smooshed into cavernous, towering cities on the non-arable land. Asimov quotes the population of this dystopic, crowded planet as eight billion. For those of you keeping score at home, the real world's population is likely to surmount this figure by the end of the next decade. Trantor, his planet-spanning city in the Foundation series, has a similar seemingly-undersized population of 40 billion.
- Averted (as seen below) by Coruscant, which apparently has a population of roughly 1 trillion. While that figure would require a lot of Applied Phlebotinum to maintain, it's reasonably accurate in terms of available space on an approximately Earth-sized planet.
  - Coruscant is still a pretty bad case of Did Not Do The Research since, well... just look at this , this, this, and this.
  - Given the sheer size of the Star Wars universe and the fact that the technology is, well, sufficiently advanced, it's quite possible that the Galactic Republic and Empire really do have the resources and equipment to maintain a planet that would consume such an enormous amount of food, to process the waste of a trillion people, and so forth.
  - What's more, who says all the aliens on Coruscant have to eat solid food? Or produce waste? Or maybe some of them eat waste? Let's not get into that?

Energy: Writers routinely grossly underestimate or overestimate the amount of energy or power needed to do something spectacular.

Examples:

In Doctor Who, the Slitheen scheme to use the world's stockpiled nuclear weapons to "reduce the planet to molten slag". In fact, the Earth gets more energy from the sun every hour than this. It'd not be enough to do more than lightly toast the surface.
- Even worse than this is the episode "Journey's End" (season 30 spoilers), where 25 strategically placed nuclear bombs are meant to be enough to destroy the entire planet.
In Space1999, an explosion at a nuclear waste dump literally accelerates Earth's moon to a speed that defies the laws of physics. In fact, the energy required to get the moon out of orbit is more than enough to completely pulverise it.
In the Back To The Future films, time travel needs 1.21 Gigawatts, the amount of power released by a lightning bolt. The same amount of power can be obtained by burning a tankful of gas per second - powerful, but not as unthinkably great as the films implied. The big issue really was getting it all at once, the difference between average and peak power. The tankful of gas would have had to have been burned up in under 10 microseconds, the same period of time as a lightning bolt lasts. (This is what capacitors are for, not that capacitors with that kind of capacity are cheap or small.)
- The problem here is one of units, rather than scale. A Watt is a unit of Power equal to one Joule of energy per second. Electricity is measured using Coulombs, Amperes and Volts. A large modern nuclear power plant can produce 1.21 Gigawatts of power, or 1.21 Billion Joules Per Second. A bolt of lightning has a discharge energy of up to 300 Gigajoules (thank you Wikipedia). Now say "ONE POINT TWENTY-ONE JIGOJOULES!" with a straight face.
- We don't know how the machine works, nor are we meant to, really. There's nothing necessarily wrong with the idea that the machine requires a certain peak power output in order to do its magic time-travel thing. It's certainly no more absurd than the idea that it has to be traveling at a certain ground speed (relative to the Earth's surface, I presume) to function.
Iron Man (The Movie) has a small generator that produces 360 Gigajoules per second (360 gigawatts). Using the above as a frame of reference, that's nearly 300 times the amount of a modern nuclear power plant.
- Then again, considering all the stuff the suit did, it might actually require that much energy. This is more a case of Unobtainium then lack of scale.
In V4 Legion Of Super Heroes, the moon gets blown up. Earth hardly notices, even though just a few chunks of it should wreak disaster on the Earth equivalent to being hit by hundreds of asteroids at once. Later on, the Earth is blown up and said to damage the moons of Saturn, when the effect should be unnoticeable.
In Ben10 the self destruct mechanism on the Omnitrix releases enough energy to destroy the entire universe. One of many problems with that idea is if you ever got that much energy into one point (assuming it existed in the first place), the total absence of energy from the rest of the universe would destroy it anyway.
In the Riverworld series, food is provided by an energy-to-matter conversion. Three times a day, each Grailstone blasts out enough energy to create food for seven hundred people, and half that energy gets wasted into the air. There are some 20,000,000 Grailstones on the planet. Just for clarity, a one-kiloton thermonuclear explosion converts about three grams of mass to energy. The Grailstones should blow the atmosphere off the planet at breakfast, lunch and dinner.

Velocity: Forget "warp speed", "hyperspace", "slipstream" and all that jazz. Space ships can travel at speeds of "fast enough" and "not fast enough". These speeds are plot-dependent, and have little if anything to do with the actual distance between places. In fact, in a commentary for Babylon 5, J Michael Straczynski actually says that White Stars travel "at the speed of plot."

Examples:

The length of subjective time it takes to get from anywhere to anywhere else via TARDIS in Doctor Who is random (but then, the navigation is notoriously dodgy).
Star Trek is even worse: the USS Enterprise traveled to the edge of the galaxy (in "Where No Man Has Gone Before" and "By Any Other Name") and to the center of the galaxy (in Star Trek V) in the space of a single episode. The trip from one galaxy to another would take about 300 years. Yet in Star Trek Voyager, when ships were about a thousand times faster, the estimated travel time to Earth from the opposite side of the galaxy was upwards of 70 years.
In Star Trek Enterprise, the Klingon homeworld is several days' travel from Earth, which would put the two empires right on top of each other, given the increases in cruising speed in the other incarnations of the franchise. (Though one interesting exception: in the first episode of Star Trek Enterprise, Trip describes the ship's top speed in terms of how long it would take to travel to Jupiter and back, and he's exactly right, based on conventional estimates of how warp factors work). In fact if you use those same calculations, the Klingon home planet would be two and a half lightyears from Earth; the nearest star to us in Real Life is four and a half. Missed it by that much.
Space 1999 comes through again by having characters track the approach of faster-than-light craft optically, and by allowing floating space rubble, conventional rockets, alien spacecraft, and a moon hurtling interstellar distances in days to be in range of each other for exactly as long as the plot demands.
Space Cruiser Yamato has the Earth see the approach of the Comet Empire, even though it's light years away and the light from it wouldn't reach us yet. Also, the Comet Empire is the size of a small planet - big, but not big enough to be seen at that distance anyway.
- In the Americanization, Star Blazers, the newly launched Argo makes its first hyperspace jumps, traveling light years from Earth to Mars. Must have been a bit of a detour involved.
Starship Troopers (The Movie)once again shines through with a huge asteroid passing a battleship vastly distant from Earth, with the same asteroid striking the Earth mere hours later. To add insult to injury, the battleship was also moving towards the asteroid, yet the asteroid seems to slowly pass by happily ripping off a section of the ship as it does so - suggesting the ship is, in fact, flying backwards at a velocity very close to but slightly slower than the asteroid.
Subverted in Spaceballs:
Colonel Sandurz: Prepare ship for light speed.
Dark Helmet: No, no, no. Light speed is too slow!
Colonel Sanders: Light speed too slow?
Dark Helmet: Yes. We're going to have to go right to...Ludicrous speed!
Colonel Sandurz Ludicrous speed? Sir, we've never gone that fast before...I don't know if the ship can take it.
Dark Helmet: What's the matter, Sandurz? Chicken?
Justified in Animorphs where travel through Zero Space is explicitly stated to be relatively random, where the same distance can take either hours or months, depending on how Zero Space shifted.
In the sequel to System Shock, it's discovered that a piece of the space station which was jettisoned by the player in the first game has crashed on a planet in the Tau Ceti system - crossing a distance of 12 light-years in a mere 30 years. This would require the ejection charges to have kicked the module loose at about half the speed of light...
- Unless the occupant got clever and built a propulsion system for the module.

Probability: You don't just beat the odds in Sci Fi. When The Spock gives you the probability of your success, it's usually in the realm of "Slightly less likely than the possibility that all the molecules in your underwear will spontaneously jump one foot to the left". This is to show that your pluck and determination can overcome anything, but, honestly, we're talking about levels of improbability that defy the laws of physics (see Million To One Chance).

Another tenet of probability which science fiction has trouble with is "The Butterfly Effect". While writers have long been glad of the general understanding that even very small changes in the past can have very major effects in the future (see For Want Of A Nail), they seem convinced that these changes will all happen at a macro level with everything somehow remaining the same on a micro level. Sliders was a notable offender on this count. See In Spite Of A Nail.

Another probability-related issue is the effectiveness of poisons or radiation exposure. In real life, a near-fatal dose has near-fatal effects, and the only way to tell if the dose isn't fatal is to see if the patient dies. In television and film, you're either dead on the spot or perfectly fine. (This may have been influenced by the classic RPG Dungeons and Dragons, which was infamous for "saving-throw or die" poisons and spells.)

Examples:

Neon Genesis Evangelion loved to state bizarrely definite probabilities of battle plans working. The odds were invariably something along the lines of "0.000000001% chance of success", and, of course, they always worked.
Subverted in Tengen Toppa Gurren Lagann, in which the characters beat the odds even when the probability of success is precisely 0%.
Literary example: In the short story A Sound of Thunder by Ray Bradbury, dinosaur hunters are warned not to step off the time machine they came in, since any slight change could alter the future unpredictably. Naturally, someone does, stepping on a butterfly and changing the future. Now, they do explain that the dinosaurs they're assigned to hunt were about to die already, thus not changing the future. However, why doesn't the very presence of the time machine change things? Although it floats to prevent it from touching anything, it does displace air, it blocks the path of animals and sunlight, and the humans themselves are releasing germs and skin cells and flying metal into the environment; it seems like it would cause as least as much disruption as a crushed butterfly.
- In the pilot of Seven Days Parker puts his savings on a very closely decided basketball game that he already saw on TV. The game goes the other way for this reason. Why he doesn't learn from this and bet on things less likely to be affectedy by chance, like large stock market swings based on mergers and budget disclosures, is not discussed.
- Parodied in a Treehouse of Horror episode of The Simpsons. Homer takes his homemade time machine to the Cretaceous Period and causes ridiculous changes to the timeline, such as sitting on a prehistoric fish causing Flanders to become the evil overlord back in the 20th century.
Literary example: In Robert A Heinlein's Moon Is A Harsh Mistress Mike the computer continuously updates the probability of success for revolution. The probability starts from 1 out of 7 and the number 7 goes up (making the probability go down) after a step in the plan succeeds; since the success of the whole plan is contingent on the success of the part that succeeded, the probability should be going up and the number going down. Later it is revealed that these numbers were faked to encourage the protagonists and the real probabilities were much lower.
Wild Arms 2 featured a story arc where Ashley had been killed, but instead of dying had been transported to some parallell universe or somthing. The crew procede to attempt to bring him back somehow. The probability is given as a number so close to zero that I don't want to say it. BUT NOT ZERO, so as a result the probability is actually 100% and alls well that ends well.

Unitless Numbers: Writers do this with discrete quantities, too - such as stars in a galaxy, or bacteria on a plate.

Examples:

Star Wars - It is generally given that there are 1 million habitable worlds in the Galaxy (and 2 million sentient species, which, given that most worlds are seen to support only one, means that hidden somewhere in the Unknown Regions there must be a Planet of Leftover Species). There are roughly a trillion beings living on Coruscant alone... when the Kaminoan prime minister thinks it's wonderful that he's able to announce that a million "Units" are almost battle-ready, many people take it as individual troopers. One trooper per inhabited world? Yep, that's going to keep the local systems in line. A later Ret Con gives the production figures at 3 million, which isn't much better. The number of droid troops varies wildly depending on which source you read, from "1 million produced per year" to "several quintillion". There have been attempts to partly justify this as propaganda, bad intel and misinformation-sowing on both sides of the war. The real culprit, of course, is that nobody ever said what those "units" meant. Could be one clone trooper, could be a whole army of 'em.
- A similar problem: all droids have a four-characted "designation", each apparently a combination of non-case-sensitive numbers, with a dash somewhere in it (i.e. C-3PO and R2-D2, or IG-88). Assuming each droid is giving a unique name with this setup, there are "only" 5,038,848 possibilities (0-9 is 10, plus 26 letters, so 36^4, times three for the number of places to put the dash) - which, considering droids have been around for at least the better part of 4000 years, and there are quite a smegload of them, would run out fairly quickly.
  - It gets worse when you realize that parts of those designations, like "R2" and "3PO", are apparently universal to that particular model of droid: All R2 droids are designated R2-** (where ** is another letter-number combo), etc.
  - Nobody's saying those ID numbers are unique, though. We probably just never have one R2-D2 unit meet another because it's confusing. Also, they're not limited to one-digit numbers. Obi-Wan's astromech droid was named R4-P17.
  - Possibly the droid's serial number is actually fifteen or twenty characters long, but as a social convention droids announce their "name" as the last (first?) few characters. In which case, "R2-D2" might be a nickname for some massive, unmemorable string of random letters and numbers.
Warhammer 40000 has this off and on, likely as a result of the huge number of different writers and developers who have worked on it. At times, distances, timescales and the number of soldiers needed to launch a sector-spanning crusade are handled "realistically", but just as often a few hundred Space Marines purge an entire world in a few weeks.
- It depends on whether authors used real tabletop rules to determine force requirements, or simply run their imagination wild. Designers in Games Workshop even hung a lampshade above all this mess, introducing so called Movie Marines set of rules that mimick the ultra-badass Marines from the fluff.
Doctor Who in its new incarnation seems rather fond of comically large numbers: five million Cybermen; the year 5.5 billion;the year 100 trillion; six million Racnoss; a million Adipose, 6 billion Toclafane.