Richard Garriott is a video-game developer and entrepreneur who is also an avid magician. On October 2008, he flew to the ISS on board of a Soyuz rocket as a private astronaut. During his time on the ISS, he performed several magic tricks.
One of his magic tricks involves a hammer that floats and a card that seem to fall down as if it is pulled down by gravity. Flat-Earthers were unaware it was a mere magic trick and wrongly assume it demonstrates things are falling down in the ISS, despite other objects in the scene that float.