And every man—even criminals, thugs, and hooligans—wearing suits.
Another thing that’s really starting to date movies/TV shows are CRT televisions and computer monitors. It’s particularly jarring in anything set in the “future”, especially when the film’s setting is still in the future. Babylon 5 tried their best to disguise their monitors, but the curves are still pretty obvious. I’ve also noticed how jarring it is to watch a TV show on DVD that was shot in 4:3 aspect ration on a widescreen TV.
Yeah, me, too. 
We had voicemail through AT&T for a number of years. We hated it. The commands were strange and unintuitive, and once you saved a message, retrieving it was a PITA. We actually switched to a cordless phone with a built-in digital answering system a few months ago.
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A crime-ridden New York City in decline rather than a place that is fabulously wealthy: 1970s through the middle 1990s.
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The Soviet Union as an enemy, evil Russians, and the like.
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Anything taking place in the northern suburbs of Chicago or the San Fernando Valley: the 1980s, fer sure.
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Computers that aren’t connected to the Internet: early to middle 1990s.
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Yiddish-oriented humor: seems to have faded away since the 1980s.
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CB radios: middle 1970s to early 1980s.
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Rapidfire nasal speech (in the US): 1960s and earlier, extending into the 1970s for Quinn Martin police dramas on television.
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Generous female public hair: pre-1995.
Walkmans.
They’re funny to see now, and you’ll most often see them on throwaway background characters in a park or street scene.
And, on a similar note, ghetto blasters, most often seen in the aforementioned New-York-in-decline movies.
And, on a similar note, breakdancing, also usually in the context of a dying NYC.
Rotary dial phones.
Walking from the ticket counter directly to the gate to board a plane. For that matter, having family or friends come to the gate to say goodbye/meet the plane.
Analog tuners on radios and tv’s.
Computers without a mouse, or with a monchrome monitor.
For that matter, walking out onto a runway to board a plane.
The same could be said about body hair on men.
I know it’s implied, but I’ll say it out loud. Not just breakdancing. But breakdancing on cardboard on random street corners with two or three friends taking turns. Maybe a couple of girls hanging out watching as well.
Oh, a few more early 90’s ones for me. In fact, these not only scream early 90’s, but early 90’s in California. Walking around on the beach with the white sun tan lotion on your nose. Weighlifting on the beach. The whole Valley Girl thing.
Earth Girls Are Easy kinda nailed the whole early 90’s California beach stereotype movie. (Good movie too.)
Metal syringes, glass IV bottles, incandescent lights, nurses with those little white hats (I know of one nurse that still wears one),
Mildred Pierce. Try as I might I can’t find the scene on youtube.
CRT monitors.
Phone Booths.
B&W TVs.
80’s Big Hair.
Science Fiction movies that have computers with huge walls of blinking lights.
Main frame computers (with reels spinning back and forth).
The copyright date on the back of the DVD box.
I’m amazed at how NOT dated *Jurassic Park *is in many ways, but there are a few things that remind me that the movie did, in fact, come out in 1993. Most of these are computer-related. The most glaring one is when everyone gets into the state-of-the-art tour vehicles and Lex gushes over the "CD ROM!!! :eek: " dashboard computers. Also, the shiny new “digless” surveying equipment that they roll out at the dig site in Montana isn’t exactly cutting-edge anymore. (edit: oh, and when they show the Jurassic Park tech in his “virtual reality” equipment? LOOOOL)
Also, a lot of people are jarred by outdated haircuts. What’s almost as obvious for me are the huge-ass eyeglasses that pretty much no one wears anymore,like the ones on this dude.
Surprised nobody’s mentioned:
VCR’s
DVD Players
Projectors
(Cuz, you know, they “date” movies) 
(Work with me people!)
Even better: breakdancing contests between two rival posses with everyone wearing matching sleeveless shirts, bandanas, and possibly Zubaz like they’re sports team uniforms or something.
And holding switchblades…with their wrists tied together…and breakdancing with roller skates on.
ETA, obviously, that was a joke, but the Michael Jackson red leather jacket with the zippers does show up from time to time in early 90’s movies.
I was re-reading a Nero Wolfe novel, and I was struck again by the fact that people had to spend so much time trying to track each other down by phone.
In contrast, we just generally call cell phone numbers first.
Oh, and my husband and I HATE voicemail, it’s not at all user friendly, and the messages are impossible to retrieve, so we have an answering machine with the blinky light.
I can remember not that long ago, before cell phones when we would send out delivery guy out on the road (and this was extremely common for any one that had delivery people). If for some reason you needed to get a hold of them, for example, you needed to have them come back, or stop and pick something up), we’d have to start calling all his stops and asking if he’d been there yet. Eventually, you’d find one of the stops that he hadn’t been to yet and ask them to have him call in and then hope that they passed the message along.
When ever people eschew cell phones, I always try to explain how it revolutionized the freight industry. It saved, even a small business like us, a ton in hourly wages and gas not having to send someone all the way back out to basically where they just where to do something because we had no way to get a hold of them.