Deus ex machina solutions in films provide unsatisfactory endings, and these great uses of a Chekhov's gun setup are the perfect antidote.

Whether it's in the title, like Knives Out, or simply set up during the story, the concept of Chekhov's gun is a recurring element in film production. The idea itself is pretty simple: an object should be set up beforehand in order to establish its importance in order to have a satisfying payoff. These are the items that are hinted at, talked about, or showcased early on, so that the audience gets a great 'I knew it' moment - or sometimes, a rewatch to notice all the times that it has been referenced before the big finish.

Named for the playwright who coined it, the idea has seeped its way into pop culture as well as the movies and TV shows audiences around the world love. Which movie examples did Redditors love the most?

Few 1970s films have terrified audiences more than Jaws, with the shark-attack moving driving people away from the beach in droves that year, while also having an indelible mark on cinema history. Redditor vietcongagent cites the air tanks as a great Chekhov's gun.

Related: 10 Best Shark Attack Movies, According to IMDB

They conceded that it's "Not exactly the most subtle, but it makes for that epic finale." The tanks are quite well set up with Hooper's line "You screw around with these tanks, and they're gonna blow up!" and seeing Brody take the shark down with his ingenuity here is a satisfying, "epic" way for one of film's most iconic monsters to go down.

There are plenty of hidden details in The Fifth Element viewers missed, but one that definitely isn't missed, as Tink2013 points out, is "The matches in The 5th Element," which definitely qualify as a Chekhov's gun. Earlier in the movie, when Korben lights a cigarette, it's clear that he now has only one match left, which he has to use at the end of the movie to start a fire.

This subtype of the Chekhov's gun, where a hero is in desperate need of a solution and remembers they have something at the last second that saves them, may be a cliché in filmmaking, but it's better than the alternative. Without a proper setup, there's no satisfaction for the audience, since the solution seems to come from thin air.

By the end of the first film, the Gremlins have committed several real-life crimes that helped cement the second generation of mogwai as terrifying creatures, and so it's satisfying to see Billy actually take them on. As GraveRobb says, the swords on the wall are set up brilliantly.

The sword "falls down everytime someone comes home" in the film, which makes its presence abundantly memorable for audiences, even though sometimes it's only communicated off-screen through sound. "when billy pulls the sword off the wall to battle the gremlins ... we don't question it." The obvious set-up also means that the entire audience gets a satisfying "aha" moment with the reveal.

M. Night Shyamalan is a very deliberate filmmaker, and his penchant for twists is legendary, but for his trademark twist to work, it has to make sense in hindsight, so (especially in his early films) he sets it up explicitly. RayAnselmo shows how the filmmaker does it with "Joaquin Phoenix's baseball bat in Signs."

Related: 10 Things You Might Have Missed About M. Night Shyamalan's Signs

The bat is there because Phoenix's character is a former baseball player. So, he both uses it as a weapon on its own as well as to smash the glasses of water, a substance that harms the aliens. Shyamalan's slow lead-up gives the audience enough time to come to the same realization the characters do at the same moment they do.

Toy Story's "little green men" are established as being obsessed with the claw all the way back in the 1995 first movie. It's a funny gimmick that makes sense with them being in a toy claw-machine container. But DarrenEdwards pointed out how Toy Story 3 brings it back in an amazing way.

The LGM go off to the crane because of their obsession, but then that crane is what saves the toys from their moment of death. This "seems like Deus Ex Machina, but viewed as a story in three parts this works." Audiences cheered with gratitude while also laughing at the fact that these claw-loving side characters managed to save the toys because of this.

In response to Thor's hubris at the beginning of 2011's Thor, Odin banishes him to Earth and places an enchantment on his hammer that means only those worthy to wield it can. This allows for a great setup and payoff moment in Avengers: Age of Ultron, points out gummitch_uk.

"My favourite [Chekhov's gun example] is everyone trying to pick up Thor's hammer near the start of Age of Ultron" they say. It allows for an incredible moment later when Vision effortlessly lifts the hammer in front of all the Avengers. The great thing about this one is it pays off once more, in Captain America's awesome Avengers: Endgame moment when he epically wields Mjolnir.

One of the things fans might know about Back to the Future is that its sequels were shot back-to-back in part because of budget, but also because they were envisioned as a single story, which allows for Part II to set up aspects that fans would later see in Part III. yakusokuN8 points to the bulletproof vest as an example.

Biff watches A Fistful of Dollars in Part II and declares "how much he loves the fact that Clint Eastwood's character uses a steel plate as a bulletproof vest." Then, in Part III, Marty is revealed to have survived a shot from Biff's ancestor by using the same technique. The benefits of back-to-back filming!

Reddit user mikeyfreshh's favorite Chekhov's gun is "The flamethrower in Once Upon a Time in Hollywood." Quentin Tarantino's ninth film finds the director no less in form than he has been for the past three decades of his career, and was an exciting penultimate movie from him, topped off by this moment.

Previously, Rick Dalton complains about how hot the flamethrower is, and yet he keeps the prop, which the movie shows. It's a stunning final moment when he steps out of the shed and uses it on Sadie. It was so iconic, in fact, that according to another user, stunts002, said "Here in Ireland people don't clap during movies" but in that moment "my theatre went nuts cheering and clapping."

Knives Out has a title that perfectly fits its story and genre, with the murder victim having a circular collection of knives around a chair in his house. This visual was stunning enough to be included in marketing, but mrbadxampl loves "the stage prop knife in Knives Out."

Related: 15 Hidden Details You Missed In Knives Out

It's set up in two different ways, with both the display downstairs and the murder victim, Harlan, talking about the prop knife, as a responding Redditor added. It's left unspoken-of until Ransom tries to murder Marta at the end, seemingly killing her until it's revealed that he messed up and grabbed a prop.

Edgar Wright's usage of Chekhov's gun setups are the stuff of legend, but the one that several Redditors pointed to, including Low_Mark6639, was "A literal gun in the Winchester in Shaun of the Dead," to which responder maximfabulosum agreed: "Truly epic."

The Winchester bar is named for the rifle which hangs on its wall, which Shaun discovers still actually works when his group takes refuge at the bar from the zombie horde. There are plenty of other examples of Wright cleverly hinting toward later events in that one movie alone, but for a prop of his, few are as iconic.

NEXT: 10 Movie Props That Were Shockingly Easy To Make

Ryan Ten is a list writer for Screen Rant and self-published author on Amazon. He is passionate about movies, TV shows, comics, and video games that have a compelling story to tell.