Calvin and Hobbes, which ran from 1985 to 1995, is considered by many to be timeless. However, the 21st century saw a lot of social and technological changes that no one predicted, so there are some moments that clearly date the work.
- A few of the '80s strips have Calvin referencing VCRs and records, commenting on New Wave Music fashion trends, comparing his dad to Gene Siskel, or a couple of Cold War references. The comic books that Calvin devours are clearly from the Dark Age of the medium's history.
- In one early story arc
, Calvin rents out a VCR and several VHS tapes from a video rental store. Aside from the reference to the VCR (further dating the strip to before 2000, when VHS tapes were succeeded by DVDs, which themselves have been largely, though not entirely, supplanted by Blu-ray and online video streaming), video rental stores were an industry that thrived from the early 1980s to the mid-2000s, but are now almost totally extinct.note - In one strip, Calvin references the advice column Dear Abby, which peaked in popularity in the 80s, while a 1986 story arc had Calvin reference The Elephant Man, which only came out a few years prior, a 1986 Sunday comic mentioned Don Johnson, the star of the popular 80s Buddy Cop Show Miami Vice that had just premiered, in one 1986 strip Calvin says "it's Miller time" as the punchline, and the 1989 camping arc had Calvin's dad referencing Kodak, which financially declined in the late 90s and declared bankruptcy in 2012 (several jokes revolving around Calvin wasting photography film also became outdated with it, since the vast majority of cameras are digital now, making it impossible for Calvin to stall out his dad by making funny faces until he runs out of film anymore).
- One story arc has Calvin lock Rosalyn out of the house. If she'd had a cell phone, the arc would've ended much quicker (unless Calvin was clever enough to somehow trick her into going outside without her phone). Another story arc has Calvin steal Rosalyn's school notes and threaten to flush them down the toilet, but this would have easier to avoid now had Rosalyn typed up the notes on a laptop like many students do nowadays, or texted a friend in the same class for a picture of their notes.
- Watterson also noted that Calvin's household had a few appliances, such as a rotary phone and an antennae TV with dials rather than buttons, which were considered outdated even back then, but he drew them anyway because he felt they had more personality. It's also justified in that Calvin's dad was a bit of a Luddite.
- This also applies to many of the general aesthetics of the strip's setting, which intended a broad late-twentieth century feel that somewhat dates the strip even more because it often references entities and conventions which were much more prevalent during the 50s to 70s when Watterson himself was a kid, and would still be recognizable to many readers during the strip's original run from the '85 to '95, but are now lost on most 21st century readers due to having slipped into obscurity since then.
- The strip existing before the Internet is very obvious at times:
- In one of the later strips, Calvin asks his dad why their computer doesn't have internet, and his dad, being the luddite he is, retorts that it's bad enough they have a telephone. While this may have been a less extreme opinion back in the early 1990s, nowadays, any middle-class American would have a very hard time attempting to justify not having internet. Anybody with beliefs like Calvin's dad would be ridiculed. In this one comic, the word Internet is not even used, and online is spelled as "on-line", showing that the strip was written before the words became commonly used, since it just predates the popularization of the internet.
- Calvin's obsession with television and his dad's aversion to it was an extremely frequent recurring joke. Nowadays, the sentiment that "TV rots your brain" has been replaced with "too much internet/phone use/social media rots your brain" as The New Rock & Roll.
- A few strips had Calvin call the library for information on something ridiculous, only to get rejected. In a few other strips, he tries looking something up in a dictionary or encyclopedia ("Can you believe the encyclopedia doesn't have an entry for "hotwire"?"). By the mid-2000s, he would search all of this online and find out instantly.
- Another time, Calvin had to make a diorama of a desert for a school project, and he complained that he didn't know what a desert looked like. Hobbes suggested he get out a book and Calvin refused to go to the effort. Another story arc had Calvin needing to do an assignment on bats, but he refused to go to the library to do research. Nowadays, the discussion would have concerned him using the Internet instead (although Calvin would likely still refuse to look it up regardless, not wanting to go through any efforts to do so).
- One story arc has Susie forced to partner up with Calvin for a group research project. The two spend the entire school week at the library (although Susie is the only one actually doing any work), and Susie knows Calvin isn't working on the project over the weekend because he isn't at the library. Nowadays, Susie would have no way to know, nor would the two had to have spent so long in the library, because they could find all the information they needed online and wouldn't even have to meet up in person. Calvin could have even rushed his half of the assignment with factual information by looking it up on his phone rather than making it up wholesale. Whether he actually would have is another question entirely.
- Similarly, the Running Gag of Calvin's dad making up random nonsense "facts" to trick Calvin could be easily refuted these days because Calvin could easily look anything he wanted to know up on the internet to verify, or more likely, he wouldn't need to ask his dad at all.
- Another Running Gag was Calvin calling the hardware store to request buying some heavy duty explosives or machinery, only to be rebuked or have to hide the call from his parents. The gag wouldn't work nowadays since Calvin could just go online to order whatever he wanted without needing to talk to anyone. A child attempting to get his hands on bombs, grenades, machine guns, etc., would also be a cause for serious adult alarm today instead of being laughed off as ridiculous.
- Not to mention that the sheer grotesque creativity of Calvin's snow sculptures would surely go viral online today considering someone would take pictures so the world could get a load of an obvious child prodigy in art.
- One Running Gag was Calvin hanging up on any incoming calls for his parents, because he's too self-centred to take a call for someone else (and Calvin's technophobic dad refusing to get an answering machine to easily solve this issue). The joke wouldn't work nowadays for multiple reasons. First, most modern phones automatically have voicemail, secondly, there's the alternate and faster options of email or texting, and thirdly, nearly everyone has a personal cellphone now.
- Many strips highlight Calvin's tendency to wake up at an ungodly hour on Saturday to watch Saturday Morning Cartoons. This type of programming block went into decline near the end of the strip's run with the rise of syndication and cable networks, and stricter regulation of children's television.
- One such strip had Calvin waking up so early on Saturday to watch cartoons that the channel was only showing a test pattern. Modern readers might not even know what that means since test images went out of style in the 1990s in favour of 24-hour programming.
- One strip note mentioned Sears and Kmart, two American department store chains which peaked in the 1980s and early 1990s (the period when the strip was running) and would have been Household Names at the time, but have now both filed for bankruptcy and are vastly dwindling. Many newer readers may also be confused what a "blue light special" is (Kmart more or less phased out their signature blue light special in 1991 because its popularity had begun to wane, only rarely bringing it back for short periods to take advantage of nostalgia).
- A few strips have Calvin and Hobbes left alone in the car while Calvin's parents shop - something that Watterson notes was considered perfectly acceptable when he was a kid, but even at the time he was writing would be more likely to bring police involvement (mostly due to increasing awareness about the dangers of heat stroke for children or pets trapped in a car); not having been a parent himself at the time, he "missed some of the memos."
- Calvin's Free-Range Children lifestyle, with his parents frequently kicking him out of the house to spend the day outside. It was already getting outdated by the end of the series, but it's practically unthinkable now to let your kid wander alone in the wilderness or around town without supervision (or a cellphone), never mind a six-year old like Calvin. The comic began as this mindset of parenting was on its last legs in middle-class America.
- In one 1990s strip, Calvin tells Hobbes of the approaching "electronic superhighway" that will link televisions, computers, and phones across the world together to provide "instantaneous interactive communication". The term "superhighway" to refer to the advancing communicative technology of the internet was a popular one in the 1990s but fell out of use near the beginning of the 21st century. Ironically, Calvin marvelling at the future ends up dating the strip in the past.
- As noted in Science Marches On, the strip's depictions of dinosaurs very clearly cement the setting in the late 20th century, such as references to "ultrasaurs", scaly raptors (specifically Deinonychus, which further dates the strip to between the 1980s and the early 1990s, when raptors were gaining popularity in dinosaur books but before Jurassic Park came along and made Velociraptor the go-to raptor name), and an entire multi-strip arc based around the debate of whether T. rex was a hunter or scavenger, all dinosaur factoids that have long been discredited.
- Notably, Deinonychus are written out as "Deinonychus dinosaurs", as if the reader wouldn't know what they were otherwise, making it clear that the comic was written before dromaeosaurs became a far more widely known type of dinosaur after the release of Jurassic Park.
- In one of the later strips, Calvin's dad refers to car phones and fax machines among newer technologies (along with modems); and one Sunday strip has Calvin wanting his dad to fax his Christmas wish list to Santa. Both were fairly widespread in the 1980s and early 1990s, but with the rise of widespread cellphone and the internet use, have become largely obsoleted by the 21st century (car phones particularly).note Another strip has Calvin bemoaning the fact their car doesn't have a built-in cassette player, which became outdated for the same reason by the beginning of the 21st century.
- As noted in Technology Marches On, the few times then up-to-date technology is depicted (as opposed to intentionally anachronistic devices like the rotary phone or antennae television), it ends up dating the comic. For example, Calvin's mom is shown writing letters with a typewriter (by the end of the comic's run, they had been succeeded by writing programs on personal computers), Calvin is shown recording himself with a cassette tape (these were popular in the 80s and 90s, but have been succeeded by cellphones), all the cameras are film cameras rather than digital, and Calvin's dad's computer uses a bulky CRT vacuum tube monitor (phased out by LCD monitors by the late 2000s).
- For example, in one comic, Calvin tries to have Hobbes take a photo of him flying through the air after another sled crash. However, it fails because the back of the camera popped open and exposed the film. Not only does this show the strip predates the succession of digital cameras over film cameras, nowadays everyone just uses a cellphone to film anything.
- Calvin's dad having a computer only occurred very late in the comic's run, as CRT monitor computers becoming affordable and widely available only occurred at the end of the 1980s, as well as factoring in Watterson's tendency to depict intentionally dated technology in many cases (it's no coincidence almost every comic where the computer appears is used to criticize modern technology).
- In one 1995 strip, Calvin is daydreaming in class again, to the annoyance of his teacher. Calvin tells her that his "eyes were on screen saver". Older CRT or plasma screen computers used screensavers to prevent burnout if a screen is idle too long, but most modern computer monitors are not susceptible to this problem (or simply go to sleep if idle too long instead of using screensavers).
- In one 1994 strip, Calvin's dad mentions seeing cigarette ads twenty-five years ago. The strip ran on a sliding time scale and Calvin's dad's age is never mentioned, but past the early 2000s, it would be basically impossible for Calvin's dad to have seen a cigarette commercial as a kid, considering the last one aired in 1971. Tobacco advertisements on TV would be banned in the US after that. Similarly, another strip in 1992 mentions he was taught math in school using slide rules, which fell out of common use in the mid 1970s (with the rise of affordable handheld electronic calculators).
- Similarly, some strips suggest Calvin's dad was a hippy, or at least was part of the anti-establishment counterculture of the 1960s and 70s when he was a teenager or young adult, and is part of the baby boomer generation. If the comic had progressed into the 2000s, it would've become impossible for Calvin's dad to have been alive back then without being unusually old...
- Similarly, some strips suggest Calvin's dad was a hippy, or at least was part of the anti-establishment counterculture of the 1960s and 70s
- Inflation example in this 1992 strip. Calvin asks his dad why they don't have a cool sports car like in a commercial he's watching, to which his dad says that car costs $40,000. With how much inflation there's been in the past thirty or so years, adult readers nowadays would be wishing sports cars still cost that much. By the early 2020s, the average new car in the US costs over $40,000. A sports car costing $40,000 in 1992 would cost $85,000 in 2022.
- Another inflation example; in an early strip, Calvin's dad tells Calvin that it cost, on average, $100,000 to raise a child to legal adulthood (and then asking in a rather threatening tone if he should consider that cost a gift or a loan to get Calvin to behave himself). Current estimates on the average cost of raising a child to eighteen in the US during the early 2020s are around the range of $300,000.
- Another inflation example is in a 1992 strip where Hobbes asks Calvin how the movie sequels are this summer. Calvin says they're great, because he hates paying five bucks to have to deal with a new plot. Average movie ticket price in America for most of the '90s was under five dollars, but has since risen far above that. By the early '00s, it was six dollars, and by the early '20s it was well over ten dollars. Any moviegoers today would be ecstatic over five dollar movie tickets. And that's not factoring in the price of concessions, which have also skyrocketed since the 90s.
- In the infamous Sunday strip where Calvin discusses an analogy of deer shooting a man to death to cull the growing human population, he states the human population had grown to "almost six billion". The strip was published in 1995, and, needless to say, it didn't stay "almost six billion" for much longer; by the Turn of the Millennium (less than six years later) it had already broken six billion. It eventually reached seven billion by 2012, and a whopping eight billion by 2022.
- When Calvin and his parents are at the airport sending Uncle Max back home, they're shown seeing him off right as he's boarding at the terminal (as seen by the plane being right outside the window). Obviously, post-9/11, they'd never be allowed to do this. Even as the strip was ending, they'd have a hard time doing this.
- When Calvin and Hobbes go to Mars, they encounter a NASA Viking lander from the 1970s. A modern reader might wonder why he didn't encounter any of the more well-known Martian rovers, which is of course because they didn't exist until shortly after the comic strip had stopped running. At the time, the Viking programs of 1975 were the most recent successful missions to Mars, and it wasn't until 1996 (just less than one year after the last strip) that the United States resumed sending landers on Mars.
- In two different 1990s comics, Calvin tells Hobbes that he is collecting comic books as a retirement fund, satirizing the comic collecting boom of the late 80s to early 90s. Only a year after this strip, Hobbes' questioning how they could become valuable if everyone had multiple copies of the same comic became prophetic, as everyone in real life started realizing the same thing, resulting in The Great Comics Crash of 1996.
- On a similar note, one 1992 comic had Calvin asking Susie if she'd like to trade collectable bubblegum cards with him. These were a big industry from the 1950s to the 1980s, but packaging cards with gum was basically phased out around the early 90s because the gum often stained the cards, which was obviously undesirable to collectors.
- Many of the Sesquipedalian Loquaciousness comics were meant to make fun of the New Age psychobabble that Watterson hated, directly ripping from text passages he came across. This part of the joke is likely lost on readers nowadays, since the traditional New Age beliefs which became popular in the late 20th century declined by the beginning of the 21st century.
- In a few strips, Calvin and Hobbes are looking up movie or television showtimes in the newspaper. While many newspapers do still do this, the practice of actually using them to look up showtimes largely disappeared by the late 2000s, since it was much easier and more reliable to just look them up on the internet, and is nowadays considered a source of nostalgia for Gen X-ers or Millennials.
- A Running Gag is that Calvin always wants to watch trashy Slasher Movies and Exploitation Films. These were of course two genres which thrived during the late 20th century up until around the mid-90s. In particular, three movies mentioned involved cannibalism in the title; cannibal films were a subgenre of exploitation horror which boomed in the 1970s to the end of the 1980s, but is now largely forgotten outside of small cult followings.
- In one 1992 strip, Calvin asks his mother for some money to buy a "suicide-advocating, Satan-worshiping heavy metal album". This kind of music was extremely popular at the time, but declined later in the 1990s. Also, nowadays he wouldn't even need money to listen to it since music is available on the Internet for free.note
- A 1986 strip had Calvin and Susie worry they would be paddled or spanked for misbehaving in school. Corporal punishment in American schools is not so common now (Calvin and Hobbes is believed to take place in Ohio, which made corporal punishment in schools illegal in 2009).
- Similarly, a few strips have Calvin spanked by his parents for some misbehavior incident or other (though only just implied by Calvin in the final panel grouchily holding his rump with star symbols indicating pain). While spanking is still a fairly widespread disciplinary tactic, its use as such has become much more criticized since the time the strip was published (even being seen as an act of Parental Abuse) and has fallen out of favor as a "default" childhood punishment.
- In one 1988 strip, after getting subjected to another Attack Hello by Hobbes, Calvin snarks that he wishes he was a "latchkey kid". The term was popular in the 70s and 80s to describe children who came home from school to an empty house, but is generally much less well-known now because of increased stigma around leaving your children home alone and more childcare options available for parents.
- Several of the strips which show Calvin fantasizing about blowing up his school, shooting up his classmates and teacher, drawing planes bombing New York, or attempting to look up how to make bombs◊, which were played for light-hearted humour at the time, clearly set the comic in a pre-Columbine, pre-9/11 era when this was taken much less seriously (notably, Watterson got numerous complaints about the first one even back then).
- In one of the earliest strips, Calvin climbs out of his window in the middle of the night on a whim, and calls his dad on a payphone to say "It is now three in the morning. Do you know where I am?". This is a riff on a public service announcement that played frequently on television from the late 60s to the late 80s, "It's 10 PM. Do you know where your children are?". It was extremely well-known at the time, but since then has faded into obscurity. Most readers nowadays likely won't understand the reference anymore. Additionally, the fact that he uses a payphone to make this call puts it in clear view of Technology Marches On.
- In a few strips, Calvin is shown calling home from school on a payphone. These were common in schools during the 80s and 90s, but became increasingly rare by the early 2010s, when nearly every student has a cellphone and most classrooms have their own landline, so most schools have removed them because they weren't worth the maintenance costs.
- The Chickenpox Episode which ran in June 1990, at a time when chickenpox was still a common childhood illness. Near the end of the comic strip's run in 1995, a vaccine for chickenpox became available in the United States, and since then cases of chickenpox in America have dramatically fallen, making the disease far rarer to contract nowadays.
- Calvin's family's car, which is an econobox hatchback (the exact model varies between appearances, but it usually alternates between something resembling a 3rd Gen Dodge Colt or a Mk II Volkswagen Golf/1st Gen Honda Civic, with the exception of the very first strip, where it's a Ford LTD). Econoboxes were a style of automobile which rose in prominence in the early 1970s and reached its peak by the end of the decade in response to the gas shortages. They eventually declined through the 1980s and were off the market by 1990.
- In one 1986 Sunday strip, Calvin and Hobbes are shown ogling a cigarette machine. These were common in The '80s, but they began to disappear in The '90s thanks to skyrocketing cigarette prices since that decade. Then in 2010, a law was enacted in the United States that restricted cigarette vending machines to facilities where people under eighteen years of age are not allowed, therefore now making it basically impossible for someone Calvin's age to encounter one.
- Hobbes also notes that one must be 18 to buy cigarettes. In 2019, the United States raised the minimum age to purchase tobacco products to 21. However, some jurisdictions raised the minimum as early as the Turn of the Millennium.
- In one of the later 90s strips, Calvin says he's wearing inflatable basketball shoes, which was likely a Take That! at the Reebook Pump and its imitators, which were a popular fad in the late 1980s and early 1990s, but like most fads declined in popularity by the late 90s. It still works in the context of the strip, because it's a knock against television advertising influencing mainstream desires, which Calvin, despite his insistence otherwise, is not immune to.
- In the first ever strip to run on November 1, Calvin and Hobbes decide to look at the Christmas decorations in town. This was presented as a joke in 1986; it's not unheard of today for houses and businesses to start putting up Christmas decorations as early as September.
- This strip where Calvin pretends to be a pilot shows stewardesses explaining the aircraft's safety features. While not completely obsolete, many airlines today use TVs instead. Also, the word "stewardess" itself has declined in favor of the gender neutral term "flight attendant".
- The airliner model depicted in Calvin's airplane pilot fantasies are Boeing 727s. These were gradually phased out at the beginning of the 21st century, replaced by more fuel-efficient twin-jets planes that only needed two operators. The last Boeing 727 commercial flight in the United States occurred in April of 2002, while the last commercial 727 period (operated in Iran) was retired in January of 2019.
- In the first camping arc, the family packs sandals for the trip. They're referred to as "thongs" which has since become a more popular term for revealing swimsuits.
- The first time machine story arc (which came out in September, 1987) has Calvin and Hobbes trying to go to the future... the far off time period of... "the turn of the century" (for the 20th century this would be 2001). As of writing (2022), it is now nearly twice as far from "the turn of the century" than Calvin was in 1987.
- One 1986 strip had Calvin explaining how soccer works to Hobbes. It may be weird to most modern readers that he's explaining the basic rules of the world's most played sport to Hobbes as though it were little-known information, while the same isn't done for baseball or football (in fact, this is the only strip where soccer is mentioned; even croquet is mentioned more). However, at the time, soccer was a minimally popular sport in the United States, especially in comparison to football or baseball, only getting big boosts in popularity in the mid-90s. By 2017, soccer had risen in popularity in the United States to the point it was only marginally behind baseball as a favourite sport (and is significantly more popular than baseball among younger viewers).
- In one story arc, Calvin mails in four cereal proof-of-purchases to receive a free propeller beanie hat. Propeller beanies were a popular fad in the mid to late twentieth century up until the early 90s, but basically died out in 21st century (although they remained somewhat popular among tech companies as novelties for a bit longer).
- In this and some other comics, Calvin's Chocolate-Frosted Sugar Bombs cereal comes with a prize or mail-in prize like a decoder ring, a mascot toy, or the aforementioned propeller beanie. However, these gradually declined by the late 2000s because it got cheaper to put a link to an online game or QR code for something downloadable in or on the box instead. Also, cereal boxes never put the toy in with the cereal anymore because, by the beginning of the 1990s, it was deemed a potential choking hazard.
- Calvin is told it will also take six weeks for his prize to be delivered, but nowadays average standard shipping time in the United States is under three days, maybe a week at most. It's extremely unlikely that Calvin would have to wait a month and a half for something like that to be shipped these days.
- At least two strips have references to Satanism, referencing the Satanic Panic that was sweeping the United States at the time that the comic was running (Calvin, of course, is trying his best to get himself into it, but as a sheltered six-year old he doesn't have any luck).
- Numerous strips have Calvin bemoaning the fact his dad refuses to get them cable so they can watch premium television shows. Modern readers may not understand how big a deal having cable was in the 1980s and 90s (since there was no internet that you could look up shows on if you missed them on television). Also, by the late 2010s, the television market has largely begun switching to on-demand streaming services, as they became both much cheaper and far more convenient than cable.
- A Running Gag was Calvin's obsession with a magazine centering around chewing gum (which Watterson states parodied the numerous snobby bicycling magazines he came across). Nowadays, the market for niche print magazines is fading, largely because it's a lot easier and cheaper to get a wide audience on a niche topic by just making a website. It seems increasingly silly to modern readers that any kid would be so obsessed with a monthly magazine rather than just scouring a hundred different sites about gum every single day for free.
- One early strip has Calvin mentioning Halley's Comet, and thinking the world will end because comets are "harbingers of doom" (although he's just using it as an excuse not to do his homework). The strip was published just around the time the comet's most recent close passage to Earth and was part of a massive media sensation, trying to incorporate the comet into many stories released around the time (other examples include Lifeforce (1985), an episode of Benson, the novel Heart Of The Comet, The Adventures of Mark Twain, the Doctor Who serial "Attack of the Cybermen", and Night of the Comet). Ironically, because the comet was behind the Sun during its 1986 passage, it provided the worst viewing conditions for onlookers in recorded history.
- A 1992 strip has a reference to phone sex ads (although Calvin, as a six-year old who thinks Girls Have Cooties, has no idea what the appeal is). Phone sex commercials were very common during late-night television during the 1990s (in the age before the rise of the internet, which allowed for nigh unlimited access to free pornographic material). The industry, while it technically still exists, has greatly declined since the 90s due to it being far easier way to advertise sexual services on the internet, and through less awkward services like chatroom texting (AKA "sexting") or over webcam.
- One strip has Calvin listening to a "boomer rock" radio station, with the announcer also reviewing movies based off of popular 60s or 70s television shows. While "boomer rock" still remains reasonably popular today, nostalgia for the 60s and 70s... not so much (mostly due to the Fleeting Demographic of baby boomers and the oft-documented "thirty-year nostalgia cycle").
- Calvin listening to music on the radio at all. It's shown as being a portable transistor radio, but even at the time of the strip's original run the popularity of these was declining due to the increasing availability of portable music players which could play tapes or CDs (it makes sense in-universe because Calvin's dad is portrayed as a Luddite who abhors new technologies), and of course these were eventually succeeded by MP3 players and smartphones after the strip's run ended. It's very unlikely any child would be listening to the radio outside of a car ride these days.
- In one strip where Calvin attempts to buy a new pair of binoculars after breaking his dad's pair, the store informs him that a new pair would cost "one to six hundred dollars". Because much manufacturing has been outsourced overseas nowadays, a pair of binoculars now would cost much cheaper.
- Several strips have Calvin or Susie attempting to pass notes in class. This is a practice that has since fallen out of practice for one simple reason: cellphones. Why waste paper and effort sneaking notes back and forth (and risk getting tattled on...) when you can just text a friend from under your desk?
- One early strip has Calvin ask his dad, who is washing the family car, how a carburetor works (Calvin's dad refuses to tell him because "it's a secret"). Carburetors were actually used to control the mixture of oxygen and fuel in the engine, but by the beginning of the 90s, nearly all new vehicles manufactured in North America and Europe had replaced them with fuel injectors.
- In one Stupendous Man story arc, he takes the Hale Telescope lens from the Palomar Observatorynote as a gigantic magnifying glass to vaporize his school off the face of the Earth so that he won't have to do his homework. Watterson almost certainly picked this particular telescope because it was the largest telescope in the world, at the time. However, its record was beaten only four years later, and since then many larger telescopes have been constructed.
- In one short story arc, Calvin tries to prevent from being pounced on by Hobbes by wearing a mask on the back of his head like he read that people in India do to ward off tiger attacks. This was publicized at the time and it was effective... emphasis on was, because the tigers realized rather quickly that the masks were not actual faces and it didn't work anymore, rendering its effectiveness short-lived. Rather fittingly, Hobbes immediately outsmarts Calvin by attacking without sneaking up on him first.
- Two different story arcs involved the use of the Cut-and-Paste Note by cutting up letters from magazines (so the message can't be tracked by the handwriting). This trope is largely discredited in the 21st century for the simple reason that you can type up a letter using a generic font on a computer and print it out, which takes far less time and effort than cutting out and pasting individual letters from magazines. This would also mean Calvin would have never figured out Hobbes was the one sending him the anonymous insults (because his mom asks Calvin to tell her he's cutting up her magazines beforehand).
- The iconic Sunday strip where Calvin introduces "TYRANNOSAURS IN F-14s!!". The Grumman F-14 Tomcat was retired by the US in 2006 and, aside from some preserved for historical display, all remaining F-14s in the country were destroyed in 2009 (a few F-14s remain in service in Iran, although in declining number).
- A few strips have Calvin or Hobbes complaining about environmental issues, such as acid rain and holes in the ozone layer. These two specific environmental issues are hardly mentioned anymore due to stricter regulations controlling air pollution emissions. Ozone depletion ceased around the late 1990s and has since begun recovering, while acid rain prevention was actually more successful than predicted, rendering it a non-issue by the late 2000s.
- The strip's frequent Green Aesop stories were often very ham-fisted and direct, something even Watterson admitted for the Story Arc where Calvin and Hobbes went to Mars to escape pollution. However, extremely heavy-handed environmentalist stories were a dime-a-dozen during the late 20th century, when there was a much bigger push in the general public, as the negative effects of large-scale human activity became more obvious (this is the same era when FernGully: The Last Rainforest and Captain Planet and the Planeteers were created after all). Although Watterson may have considered the story a little too direct in its environmentalist moral delivery, it would've been highly typical of the time.
- In one 1990 strip, Calvin says Hobbes has denounced tuna as his favourite food because he found out that they kill dolphins to catch tuna. This was a major environmental issue in the 1970s and 1980s, but much stricter fishing regulations in the 1990s (including the invention of a "dolphin-safe" certification label on tuna cans) vastly reduced the number of dolphin moralities from trawling (although cetacean bycatch as a whole remains an issue).
- This 1992 strip depicts Calvin with a jar of Mustard. Good luck finding Mustard that isn't in a squeeze bottle these days. Even in The '90s, they were becoming rarer. However to be fair to him, some types of mustard are still produced in Jars - Generally brown or dijon mustards.
- While this strip from 1986 still has some punch as a general anti-war message, the two immediately "killing" each other has lost some weight since the end of Mutually Assured Destruction. Then there's Calvin dubbing Hobbes "the loathsome Godless Communist oppressor".
- In one 1995 strip, Calvin tries to get out of class with a note from the president saying he's urgently needed. Unsurprisingly, Miss Wormwood doesn't fall for it and sends him back to his desk, where he mutters that he needs to learn cursive (ignoring the fact that the note was also written on lined paper). In the 21st century, cursive as a skill is dying out due to being replaced by keyboard typing (and the tendency for cursive to be difficult to read), and nearly all professional notices are typed now. No child would ever say or think "I gotta learn how to write in cursive" nowadays.
