Any example of firearms being lazily or incorrectly depicted, whether for dramatic effect or simply because the writers didn't bother to check.

Rango (2011): Rango's Single Action Army is depicted with a swing-out cylinder. While extremely common in revolvers nowadays, the SAA used a loading gate, the cylinder was unable to be moved from its position without disassembling the firearm.

Ant-Man (2015): During the mexican stand-off, all of the characters are seen cocking the hammers of their Glock pistols, of which all models have internal hammers.

The Walking Dead S1E1 (2010): Rick tells the new guy to take the safety off his Glock 17, which has no external safety mechanism. Instead, he simply wiggles the slide release.

Grand Theft Auto IV (2008): When reloading the "Carbine Rifle", Niko will yank on an imaginary charging handle and wills 30 new rounds into the magazine with the power of happy thoughts and well wishes. While crouching, he does replace the magazine, however.

Various FPS Games: In many depictions of weapons where the fire selector is visible to the player, more often than not it is set to "Safe", if not completely broken, such as the case of the M16A4 in Modern Warfare 3 (2011).

Klingons and their bat'leth. The user is definitley going to cut themself- Star Trek

Ivy's whip-sword. She's going to cut herself by accident- Soul Calibur

Jedi and Sith's lightsabers. What if you drop it does it just burn through the floor? How do you get it back? Also those sparks are hot plasma- Star Wars

Tira's razor blade hula hoop. She's going to cut herself by accident- Soul Calibur

Guts' Dragonslayer Sword would weigh anywhere from 150 to 400 pounds in real life- Berserk

Hot Fuzz: Every member of the city council is packing heat. Even the Priest

Dirty Pair Flash: Everyone packs heat. One guy's girlfriend turned out to be a robot and she's pack to the brim with firepower

Scarlet Witch (Avengers Infinity War): Elizabeth Olsen wasn't a fan of the deep cleavage her costume had.

Robin (Batman and Robin): Chris O'Donnell preferred his Robin costume from Forever more than B&R. Also didn't like how the mask was glued to his face making him sweat a lot. Probably wasn't a fan of the nipples on the costume either.

Yellow Ranger (Power Rangers): Karen Ashley didn't like wearing the Yellow Ranger outfit because instead of getting a new costume, she was just given Truy Trang's old one. She had to wear several pairs of socks just to wear the boots. Also because of the non insulated costume, and cold sets, she had to wear bandaids.

Garak (Deep Space 9): Andrew Robinson didn't like the tight clothes and prosthetics he had to wear for the simple tailor because like the character, he too was claustrophobic.

In Dandadan, Momo Ayase regularly switches outfits between chapters/episodes. You see a similar thing in The Weekenders (with Tino as an example) and Totally Spies. I think it's a nice bit of realism that's often overlooked.

Infinity gun(invincible) this weapon can basically destroy anything (viltrimites, planets, etc) however, once fired, the beam never stops it will continue to destroy anything in its path for eternity. Which is why space racer has to choose his shots wisely.

The concept of wishes (Ladybug and Cat Noir) in the show when someone makes a wish, they have to pay a price which varies. In order for Natalie to survive, Gabriel sacrifices his life for hers creating a new timeline.

A lot of action movies these days focus on fast paced clean combat of a character mowing down dozens of bad guys like John wick. So it’s refreshing to see a realistically messy and uncoordinated fight every now and then.

The stairwell fight from atomic blonde
Tony fighting ralphie on sopranos
The amazing pike battle from altariste

1. Emma Swan's leather jacket, Once Upon A Time. This was a huge part of Emma's character throughout the first 5 seasons. At the end of S5, we discover she adopted the jacket in her 20s as a sign of armor to protect herself. She ends up retiring it not long after that because she doesn't need the armor anymore. Real life reason, Jennifer Morrison was struggling with consistent migraines and had a hard time wearing the tight fitting jacket. Similarly, a lot of Emma's wardrobe was changed to match Jennifer's so she'd be more comfortable. At the time, they tried to say this was Emma's way of letting her guard down, but Jennifer ended up admitting later on that it was due to her migraines.
2. Dean's amulet, Supernatural. For the first 5 seasons, Dean was consistently seen wearing this around his neck. At one point, he even says he feels "naked" when it's off. We find out in a flashback that it was a gift from his younger brother, Sam. During a contentious time in the brothers' relationship, Dean rips off the amulet and throws it in the trash in front of Sam. The real reason for this is Jensen Ackles said the necklace was a pain in the ass during fight scenes and was always getting tangled up and at one point, chipped his tooth. So, he asked them to retire it on the show. The amulet would appear a few more times throughout the show (as it's also a connection to God in this universe), but Dean isn't wearing it.

Any weapon that utilizes a black hole deliberately.

Examples:

The special shells from Outlaw Star. The protagonist Gene Starwind manages to acquire 2 special shells for his Caster Weapon (a spell gun) that basically shoot miniture black holes. This gif shows what they do their target; its arguably one of the most intense anime deaths.

The Novacula from Foundation, a planet killing weapon commissioned by one of the Emperors. It extracts energy from the ergosphere of a stellar sized rotating blackhole to essentially create a controlled gamma ray burst. This is capable of turning planets to dust, and it can be fired in rapid succession and through FTL terminals.

1. Batman Dark Tomorrow: - Already a rubbish game, but you're supposed to deactivate a satellite with a hidden button about halfway through the game before you face R'as al Ghul. If you (obviously) missed it, his plan goes ahead and humanity is flooded. A massive 'fuck you' ending because you didn't care to look for a switch down a random hidden pathway while you struggled like hell with the dogshit controls and camera throughout the entire runtime.

2. Mega Man 1: - Currently experienced this. Almost at the end of the first Wily stage, excited to fight the Yellow Devil, you're suddenly stuck behind a massively high platform. Turns out, you needed to use Guts Man's power to uncover the hidden Magnet Beam power in Elecman's stage. So you gotta restart the whole two levels to go back and get it... No wonder MM1 isn't as beloved as the other entrees.

From the badass and inspiring to the ridiculous and cheesy to the deeply personal, I love this shit.

First picture (real life) - On the sword of Giovanni delle Bande Nere, Italian commander: "Do not unsheath me without reason, do not wield me without valor."

Second picture (Fallout New Vegas) - On the pistol of Joshua Graham, Missionary and former Very Bad Man: "And a light shone in the darkness, and the darkness understood it not."

Third picture (real life) - On the guitar of Woody Guthrie, musician known for protest songs and political activism: "This machine kills fascists".

Fourth picture (real life) - on the cannons of King Louis XIV: "The last argument of kings."

The boys

Godzilla x Kong: A new Empire

Brit

1: the seven barreled, rocket shooting, grenade launching, magazine, belt and revolver fed creature of a gun in this strike commando poster (bonus points for the guy trying to play off his negligent discharge in the background).

2: this abomination from a daredevil comic.

3: whatever it is that Chris Redfield is holding while having a stroke in the Resident Evil 1 cover art.

4: The Zip 22, from real life. Although the gun is regarded as terrible and prone to jamming, one thing I don't see mentioned enough is that to cock/unjam the gun you use the mechanism directly above the barrel, risking shooting yourself (if the gun even works enough to shoot, that is).

1. Pink donut with sprinkles (iconic donut design from The Simpsons)

2. Ratatouille (the final dish of the eponymous Ratatouille)

3. Chili dog (favorite food of Sonic which appears countless times across the Sonic the Hedgehog franchise)

4. Chimichangas (often mentioned by name in Deadpool, although Deadpool himself doesn’t actually like it and just likes saying the word)

5. Cheese gyudon (essentially the soyjack of Japan, where just mentioning it invokes the image of the loser soyjack)

1). Dungeon Meshi:
Another dwarf is flabbergasted to learn that Senshi has been using an adamantine shield as a cooking pot. And his mithral knife to cut vegetables.

2). Adventure Time:
The "Enchiridion" is a manual for heroes, and also a portal to other universes. After Finn earns it, he admits he mostly used it as a seat cushion for sitting on wet grass.

3). The Avengers:
In Endgame, we see Thor using his advanced weapon to open beer bottles.

4). The Lord of the Rings:
Sauron's ring is the key to his return to power. For hundreds of years, Gollum used it to eat goblins and fish inside a cave.

5). Dragon Ball DAIMA:
The demon realm has a legendary magic eye that grants its user insane power. It's being used as a belt buckle.

Dennis - SpongeBob SquarePants Movie

Jester - Legends of Oz: Dorothy’s Return

The three live action Peter Parkers had their respective homemade suits when they first began as Spider-Man made out of old clothes with red masks

In the MCU, Tony Stark made his first armor made out of metal pieces in a cave with the help of Yinsen to escape from his captors

Daredevil in the Netflix TV show first used tactical crack clothes with a black wood to fight crime through the first season

Genie from Disney's Aladdin is still wearing his shackles in the animated sequel TV series, despite them having famously disappeared in the movie when he was freed from the lamp

Man Ray in Spongebob Squarepants is still wearing the tickle belt in every appearance, despite having been freed from it at the end of his debut episode

Atlantis: The Lost Empire: The Trope Definer for me, The "Ulysses." Lots of Promotion for this beautiful designed vessel, it even seems Atlantean itself. 7 Hours into its maiden voyage, it gets snapped up. Chop chop. With almost all of her crew gone. Simply from the first form of defense Atlantis has. We had toys, trailers, and even the movie itself builds up the vessel as this amazing fangled thing. It didn't even stand a chance to the first guardian of the Lost Empire. Which is, Leviathan itself.

Blindsight - Peter Watts: We send the best of the best, we even send a different species of human just to have more perspective, we send the "Theseus". With all its impressive systems, an AI captain. Then they run into the Alien ship, the "Rorschach". Humans and Vampires finally working together after wars on Earth, just to make first contact on their mission.
The aliens don't fight them in any reciprocal way. They don't “defeat” the mission so much as demonstrate that the mission’s assumptions are irrelevant, like the entire expedition was built to solve a problem that was never actually there. It flips the whole concept of intelligent life on its head and is a great mind bend to this trope.

WWI - Tank Warfare: A design meant to end the war, secret funding, manhattan project tier secrecy. Armored cavalry with its own artillery onboard. Some armies train soldiers just to cope with how fearful any human should be against such beastly metal.
We deploy it out to the battlefield, immediately bogged down by some of the cruelest and man-molested terrain ever seen. Pushing the limits of mechanization at the time, they broke down often from even their own power. They're still awe inspiring in their own right, but their roll out was immediately met with tactic shifting, adaption, and their own counters.

Chem-Bag (Big Hero 6): this device can create chemical compounds using every single element in existence. You could literally build a nuke with this.

Mobile Headquarters (Ant-Man): a building that can shrink and grow to full size instantly. Imagine if someone grew it in a crowded city, or on a highway, or at an airport?

Lotus Cash Card (Percy Jackson): It literally has infinite money. If you know how inflation works this could literally wreck the global economy.

M1 Garand - The ping of the magazine when it is empty

Barret M82 - Really most 50 caliber's in film, it knocks people around and throws them around

MP5 - The classic HK Slap

1. Combat Shotgun (Fallout 3)

Odd design aside, this gun (and other shotgun-like weapons, but this is very early-game) does monstrous damage thanks to one thing: Critical Damage. For whatever reason, shotgun weapons have crazy high crit damage since they apply the critical damage on each pellet. So this gun has a base damage of 55 and a crit damage of 243 if all pellets connect, totaling in 298 damage. Oh and damage done while sneaking not only guarantees a crit, but also doubles the crit damage, so you’re looking at about 541 damage here. For perspective, the tankiest common enemy in the game has 1500 health, so that’s over a third of its health gone if you pull off the sneak crit. And you can get this off of a random low-level Raider or from shotgun traps lying around

2. Chance’s Knife (Fallout New Vegas)

This thing is deceptively good for a melee build simply because of its DPS and potential. It already does about 88 DPS with zero perks already. With perks that affect swing speed, damage, and one that adds a knockdown effect, this knife can carry you into the late game with no issues (aside from the obvious range problem). Best part? You can get it like 5 minutes into the game if you have a shovel and know where to find it

3. Shaman Stone (Hollow Knight)

This charm isn’t really as early game as the others, as you have to fight 2 bosses in order to get it. But any Hollow Knight veteran could breeze through the early game without flinching, even more so if you know some of the speedrun strategies like False Knight Skip, bench warps, and the Greenpath Skip. In exchange, you’ll get a massive boost to your spell damage, which is already super strong. The basic Vengeful Spirit already does 15 damage, which is 3 times your regular attack. But with Shaman Stone, that goes up to 20. And since Vengeful Spirit can hit a target twice or even thrice depending on the enemy’s size and movement, you can deal a lot of damage consistently. It is so powerful, speedrunners opted to go on the massive detour to get the charm, since it is crucial to beat a mandatory boss quickly