Bob Knodel was in the middle of filming for a Netflix documentary titled Behind the Curve when he realised his pricy mistake.
Seeking to disprove the mass of research led by NASA experts, he explained the particulars of the DIY experiment using a laser gyroscope.
The test involved using a camera to film through two holes, with a person standing on the other side and shining a torch back at the camera.
Mr Knodel professed that if the light can be seen with a camera, the holes in the fence and the torch all at equal differences above the ground, then he could draw a positive conclusion that the Earth is flat.
Yet, in a humorous and expensive turn of events, no light could be seen, causing Mr Knodel to mutter an awkward 'interesting' after the mistake.
Speaking on his YouTube channel, Mr Knodel has since opened up about the experiment and what it means for flat Earthers across the globe.
'What we found is, when we turned on that gyroscope we found that we were picking up a drift. A 15 degree per hour drift,' he said.
'Now, obviously we were taken aback by that,' before admitting the results were 'kind of a problem'.
'We obviously were not willing to accept that, and so we started looking for ways to disprove it was actually registering the motion of the Earth,' he added.
According to a report by Unilad, one Instagram user claimed: 'I bet he still won't accept it.'
Another said: 'Something oddly satisfying about watching a simple opinion dissolve in the face of non-rigorous methods lol.'
The failed experiment has since gone viral on Reddit, with people noticing that even after the experiment, Mr Knodel kept using 'mental gymnastics' to claim his conspiracy theory was still correct.
One person wrote: 'I've seen that clip many times but have yet to see his explanation as to how that happened.'
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