What was the first fictional movie to spawn conspiracy theories

Looking at the ongoing Matrix anniversary thread, I was reminded that not long after it came out there were people who claimed it was real – some kind of expose of the hidden horror we all experience without even realizing it.

Now I had my doubts about whether anyone could really believe the crazy, but I’ve heard so much crazy bullshit theories since that I no longer doubt some people believed it and maybe still do.

Anyway, was this the first such movie? I don’t really recall this phenomenon from any other flick? Is it the only one, or were there others before or since.

Just to be clear, I’m not talking about conspiracy theory movies like Oliver Stone’s JFK or the moon “hoax” “documentaries”, but ones that are entirely fictional that people have come to believe as true for whatever reasons.

Capricorn One might be the sort of thing you’re looking for, but I doubt it was the first such movie.

A complete WAG, but I think the early Sci-Fi movies (from the '50’s?) inspired people to believe in alien abduction. Some people really believed they were abducted and others belived them.

you know THEY write a movie appearing to be FICTIONAL only just to distract you and make the TRUTH look foolish.

Perhaps Birth of a Nation, but it really built on existing CT.

I think that movie was inspired by moon hoax theories rather than being the origin of them. I know there were people who didn’t believe in the moon landings long before it came out.

There’s a whole documentary devoted to the crazy theories around The Shining.

One theory is it has hidden messages regarding Kubrick being the in charge of faking the moon-landing.

You’re probably right, it was more of an “adding fuel to the fire” deal.

I don’t know if The Manchurian Candidate is the kind of movie the OP’s looking for but it was an early example of a conspiracy movie. It was made in 1962 which means it predates the Kennedy assassination, the Moon landing, Watergate, and other early topics for modern conspiracy theories.

Room 237
Here’s a thread discussing the documentary:

Kim Possible (Rufus vs. Commodore Puddles*):* Ron: What’s the real deal, what are you hiding [at Area 51]?

** Simms**: Flying saucers**, alien technology, **yada, yada.

** Kim**: But that means all the rumors are true!

** Simms**: Every last one of them. We’ve implemented a double-negative cover story. We make sure only to leak out information that is one-hundred percent accurate.

Ron: But then it’s not really secret.

** Simms**: That’s exactly what we want you to believe.

** Ron**: Yeah, but then… never mind.

By the criterion of “audiences believing this really happened,” it’s probably the very first moving images showing fictional events that would qualify as “first.” Given that the first moving images exhibited depicted actual events (a horse running; a train coming into a station; etc.), viewers of the first “story” (sometime in the 1890s, depending on how you define “story”) might be pardoned for believing that they were seeing what they were used to seeing: reality.

And reality-based stories were very popular: The Great Train Robbery (1903), for example, was fiction, not a documentary. But some viewers might have been confused about whether they might be watching a record of actual happenings.

Non-reality-based stories–fantasy–would have been less-likely to confuse viewers. Certainly by the time of Nosferatu (1922), many viewers would have been accustomed to the idea of filmed stories that didn’t have much to do with real life. But it seems likely that at least some people would have believed that Nosferatu (and other fantasy characters and situations) were real and existed somewhere in the world. Anyone who told them they were wrong might possibly have been dismissed as being part of a conspiracy.

The interesting thing about this sort of thing may be what you were explicitly looking for when you made the thread: documentary evidence that people believed that what they were seeing was real. One problem with finding such evidence: people a century ago just didn’t write about their personal beliefs in the proportions that people today do (hello Internet!)

Not exactly what you’re looking for, but the Coast Guard used to get letters from people asking them to rescue the castaways on Gilligan’s Island.

It’s not a movie, but the 1977 British TV program Alternative 3 might be another example.
Several conspiracy theorists claimed the program was true and not just a hoax TV “mockumentary.”

One interesting example was Trading Places. Some people at the SEC realized after the movie came out that what the Duke brothers had done wasn’t technically illegal under existing laws. New regulations were proposed and the movie was actually cited in the hearings for their enactment. Not a political conspiracy but it was a case where the government worried people might try to make something they saw in a movie real.

They Live is the obvious inspiration for David Icke’s nutbaggery.
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There’s at least one conspiracy theory that OJ Simpson was framed for murdering Nicole and Ron because during the filming of Capricorn One he learned that the moon landing was a hoax.

This is my new favorite conspiracy theory!

Those poor people!

Executive Action (1973) showed that Big Oil, the Republicans, and the CIA were behind the JFK assassination.