The Simpsons leaves fans shocked after unexpectedly airing 'series finale' episode: 'End of an era!'

Fans of The Simpsons were left scratching their heads after the beloved cartoon aired what appeared to be its 'series finale' on Sunday.

The Season 36 episode, titled Bart's Birthday, was framed as a 'Fox special presentation,' featuring former writer Conan O'Brien hosting an Oscars-like gala for the sitcom's send-off.

'It’s such an honor to be with you all for the series finale of The Simpsons,' the animated O'Brien said. 'Well, it’s true. Fox has decided to end The Simpsons. This show was such a special part of my early career, so being here means the world to me.'

He then shared clips from what he claimed were unaired attempts at the series finale, leading viewers to flock to social media to voice their confusion and outrage. 

'Wait wait The Simpsons SERIES finale WTFFFFF,' one posted to X, as another shared, 'I haven’t watched a new Simpsons episode in about 24 years but it’s surreal seeing the series finale on right now.'

Yet another posted, 'Series finale of the simpsons…end of an era,' while one lamented, 'Simpson Series finale.. They really about to be done.'

At one point, it looked like the episode would achieve something unprecedented for The Simpsons—actually allowing a character to age on their birthday. 

But Bart realizes he will turn 11, which he refuses to accept. This prompts Homer to strangle him, causing the show to glitch and reset, erasing the 'series finale.'

According to showrunner Matt Selman, the episode was a parody that examined what makes a good finale, imagining what the perfect conclusion for The Simpsons, the longest-running animated series in history, would look like if it were written by AI. 

He explained to Vulture that AI was employed to replicate all the typical 'finale' clichés—like Principal Skinner resigning from Springfield Elementary and Mr. Burns dying—highlighting the lack of creativity inherent in AI. 

'AI is good at regurgitating but not at being imaginative,' he explained. 

Selman further addressed the complexities of wrapping up a show intended for infinite continuation. 

'It can go on forever because it doesn’t have a hard canon or a dense continuity.'

The fake finale comes after viewers have been left flabbergasted after discovering that there is a secret movie hidden within dozens of episodes of the hit animated series. 

During the first few seasons of the beloved Fox show, members of the Simpsons family were often seen watching the same movie on their TV, an action-packed blockbuster called McBain.

The series would often cut away from the main storyline to show audiences a segment of the film that they were watching. 

Now, a social media user has pointed out on X, formerly Twitter, that throughout all of the episodes, The Simpsons ended up showing the entirety of the movie.

And if you put all the scenes of McBain together, it actually makes for a very exciting short film.

A user who goes by Criminal Simpsons on the platform went ahead and posted every clip of McBain that was showed in The Simpsons last week.

It quickly went viral, and many people on the web admitted that they didn't notice that they came together to form a 'coherent storyline' until now - and they were shocked over the realization.

The movie follows a rogue police officer named McBain, voiced by Harry Shearer, who sets out on a quest to out the city's senator after he discovers he's secretly running a drug cartel.

The character shares a striking resemblance to Arnold Schwarzenegger in the Terminator - and even has a similar Austrian accent.

McBain first made an appearance in the show during the season two episode entitled The Way We Was.

A clip showed him telling his boss that he had uncovered proof that the city's senator was 'head of an international cartel.'

But his boss was unhappy that he had gotten on the senator's bad side and told him he was fired. Suddenly, McBain pushed the man out the window.

In the next scene, which popped up three episodes later, McBain was seen enjoying a dinner with his partner - when suddenly, the waiter pulled out a gun and started shooting at them.

McBain's partner jumped in front of McBain to protect him and got shot multiple times in the chest.

Just before he passed away, he told McBain that his last dying wish was that he took down the senator.

Fans got an update on McBain's quest to avenge his partner's death in episode 20 of the second season.

He was seen telling his boss, who miraculously survived the fall from the skyscraper, that he needed a better gun to go after the senator.

His boss explained that a more-powerful weapon would go against regulation, but McBain was not happy with his response.

Naturally, he whipped out a massive rocket launcher and shot the wall next to his boss.

Viewers had to wait a long time to see what would happen next with McBain after that, with him not making an appearance again in The Simpsons until the ninth episode of season three.

But when animated series did finally show another segment of the movie, it didn't disappoint.

In the next scene, McBain snuck into one of the senator's dinner parties by covering himself in ice and pretending to be an ice sculpture.

While in his disguise, he overheard the senator bragging about his latest 'diabolical creation' - a drug '10 times more addictive than marijuana.'

After the senator made a toast to 'human misery,' McBain suddenly broke free from the ice, whipped out a gun, and started shooting everyone around him.

Somehow, the senator survived McBain's attack, and tricked him into eating one of his 'salmon puffs,' which had a substance in it that made him pass out.

It all came to an end in season four, episode 17, when the senator was seen discussing McBain's fate with his employees.

They promised that they took care of him and that he had an 'unfortunate ending,' implying that they killed him. 

'Excellent, with McBain out of the way nothing can stop us. Any other new business?' he asked, when suddenly, McBain popped up out of the table and exclaimed, 'Only your death.'

McBain then killed the senator's bodyguards, grabbed him, and violently threw him out of the window of the skyscraper that they were in; he landed on a truck, which exploded.

'Meeting adjourned,' he said, before a stunning red head woman approached him.

'Right now I'm thinking of holding another meeting... In bed,' he told her, before they started kissing.

The words 'the end' then flashed across the screen.

'I’m honestly surprised this was never made into a spin off show,' one person wrote on X in response to Criminal Simpsons' thread.

'It deserves an Oscar,' another joked, while someone else added, 'I never noticed this before and I glad to have found this thread. That’s was pretty cool.'

'Wow, how did I never notice this?' asked a different user. 

'This is a freaking masterpiece,' read a fifth tweet, while a sixth said, 'A show in a show. Works like a charm.'