You never notice them until someone points them out. Because they've always been that way. But once you know about them, you can't help but notice them, and appreciate how ridiculous we are in the way we have to keep things familiar.
These are all design elements on various things which used to have a function, but are now done "just for decoration" or because "we've always done it that way".
1. Slot Machine Payout Tray / Hopper
Slot machines originally both accepted and paid out cash. Modern slot machines pay out a printed receipt which you then cash at the cashier's cage. They no longer need the tray where the coins used to land, yet slot machines still have them. Some of them even play a recording of coins hitting the tray when you cash out and the machine prints its receipt!
2. Cigarette Filter Design
Cigarettes used to have filters made from cork. When they switched to synthetic filters (usually made from cellulose), they kept the printed paper on the outside in a cork design.
3. Hood Scoops
Originally, hood scoops were necessary to direct the flow of air onto the engine to help cool it. Modern cars now have air ducts from other, less intrusive parts of the car, but some cars still keep the hood scoop design. If your car has a hood scoop, put your hand in it. It may be completely closed off!
4. Fake Wood Grain Covering
Things like shelf paper, tabletops, and counters may be made of plastic, metal, or even processed particle board, but they'll still have this tacky vinyl covering with fake wood grain on it. Once you're aware of it, you'll get tired of looking at it.
How about those station wagons in the 1970s which had fake wood paneling on the sides? These things persist even when they make no sense. Who would even want to drive a wooden car?
5. Hubcap Spokes
Ever notice how many car hubcaps still have spokes in the design, as if you were still unable to deal with the concept of a tire unless it resembled a Conestoga wagon wheel?
6. Digital Camera Shutter Sound
Like the casino hopper sound, consumer-grade digital cameras still play an audio sound of an old-fashioned camera's shutter sliding and clicking.
7. Your Keyboard Layout
The standard "QWERTY" layout of the keyboard was originally designed partly to keep neighboring typewriter keys from jamming when they hit together. Other keys' placement were originally required by the limitations of manual typewriter design - for instance, the 'CAPS LOCK' key is directly over the left shift key because it used to be a physical lever that held down the shift key itself; it would lock in place until you tapped it again. Modern computers and laptops have no such requirements, of course, but the keyboard stays that way.
A whole new generation of design appendixes evolved from the first generation of computers, too. The 'scroll lock' key, for instance, comes form the days when text-only computers scrolled monochrome text on a black monitor - you'd print something out, and then hit scroll-lock to freeze the screen until you could read that screen-full of text, and then release it to get to the next screen-full...
8. Computer And Phone Icons
Computer and phone icons are a virtual forest of visual metaphors for outdated technology. Look at that hourglass! How many of you have seen one in real life? Yet we use it to symbolize time, clocks, waiting, etc. And then there's those quill pens used for writing apps, envelopes used for email apps, cartoon speech bubbles used for texting apps... How about that floppy disk icon to represent the concept of saving a document? Floppy disks have been out of common use for at least a decade now.