Can you give an example of a documentary where the person telling the story believed it to be true, but it turned out to be false?

Read also:

• What's an underrated/unknown novel or series that you think deserves more attention?
• Have you ever dealt with a Christian narcissist?
• Sean McVay: Matthew Stafford-Davante Adams relationship is "cool to watch" - NBC Sports
• Why is there so much free porn on the internet?
• Why is India lagging behind China in economic development when India is a democracy while China isn’t?
• Can trans people tell me what the criteria for a woman is excluding self identification (facts do not rely on self belief)?
• Why is that Hag Hillary Clinton so quiet these days? She is the dog that isn't barking
• Why are people of mixed race seen as more attractive than non-mixed-race people?
• What is a real life example of the Streisand Effect?
• Why do people keep complaining about how some people copy and paste the question before answering it? To me, it's very disturbing and makes me want to block and mute them as annoying whiners.
• Sometime ago, the Iranian Minister said that a US Navy aircraft carrier would be an easy target for 300 speed boats armed with Katyusha rocket launchers. Is this true?