The evidence for a flat earth is derived from many different facets of science and philosophy. The simplest is by relying on ones own senses to discern the true nature of the world around us. The world looks flat, the bottoms of clouds are flat, the movement of the Sun; these are all examples of your senses telling you that we do not live on a spherical heliocentric world. This is using what's called an empirical approach, or an approach that relies on information from your senses. Alternatively, when using Descartes' method of Cartesian doubt to skeptically view the world around us, one quickly finds that the notion of a spherical world is the theory which has the burden of proof and not flat earth theory.
97.) Mr. Hind, the English astronomer, says – "The simplicity, with which the seasons are explained by the revolution of the Earth in her orbit and the obliquity of the ecliptic, may certainly be adduced as a strong presumptive proof of the correctness" – of the Newtonian theory; "for on no other rational suppositions with respect to the relations of the Earth and Sun, can these and other as well-known phenomena, be accounted for." But, as true philosophy has no "suppositions" at all – and has nothing to do with, "suppositions" – and the phenomena spoken of are thoroughly explained by facts, the "presumptive proof" falls to the ground, covered with the ridicule it the dust of Mr. Hind's "rational suppositions" we are standing before us a proof that Earth is not a globe.
164) Analysis of many interior videos from the “International Space Station,” have shown the use of camera-tricks such as green-screens, harnesses and even wildly permed hair to achieve a zero-gravity type effect. Footage of astronauts seemingly floating in the zero-gravity of their “space station” is indistinguishable from “vomit comet” Zero-G airplane footage. By flying parabolic maneuvers this Zero-G floating effect can be achieved over and over again then edited together. For longer uncut shots, NASA has been caught using simple wires and green screen technology.

20. The common sense of man tells him - if nothing else told him - that there is an "up" and a "down" in -nature, even as regards the heavens and the earth; but the theory of modern astronomers necessitates the conclusion that there is not: therefore, 'the theory of the astronomers is opposed to common sense - yes, and to inspiration - and this is a common sense proof that the Earth is not a globe

If the Earth were a globe, people - except those on the top - would, certainly, have to be "fastened" to its surface by some means or other, whether by the "attraction" of astronomers or by some other undiscovered and undiscoverable process! But, as we know that we simply walk on its surface without any other aid than that which is necessary for locomotion on a plane, it follows that we have, herein, a conclusive proof that Earth is not a globe.

In 1610, Galileo Galilei observed the moons of Jupiter rotating around it. He described them as small planets orbiting a larger planet—a description (and observation) that was very difficult for the church to accept, as it challenged a geocentric model where everything was supposed to revolve around the Earth. This observation also showed that the planets (Jupiter, Neptune, and later Venus was observed too) are all spherical, and all orbit the sun.
156) People also claim to see curvature in Go Pro or other high altitude camera footage of the horizon. While it is true that the horizon often appears convex in such footage, it just as often appears concave or flat depending on the tilt/movement of the camera. The effect is simply a distortion due to wide-angle lenses. In lens-corrected and footage taken without wide-angle technology, all amateur high-altitude horizon shots appear perfectly flat.
Mr. J.M. Lockyer says: Because the Sun seems to rise in the east and set in the west, the Earth really spins in the opposite direction; that is, from west to east," Now, this is no better than though we were to say - Because a man seems to be coming up the street, the street really goes down to the man! And since true science would contain no such nonsense as this, it follows that the so-called science of theoretical astronomy is not true, and, we have another proof that the Earth is not a globe. 

99.) Mr. Hind speaks of two great mathematicians differing only fifty-five yards in their estimate of the Earth's diameter. Why, Sir John Herschel, in his celebrated work, cuts off 480 miles of the same thing to get "round numbers!" This is like splitting a hair on one side of the bead and shaving all the hair off on the other! Oh, "science!" Can there be any truth in a science like this? All the exactitude in astronomy is in Practical astronomy – not Theoretical. Centuries of observation have made practical astronomy a noble art and science, based – as we have a thousand times proved it to be – on a fixed Earth; and we denounce this pretended exactitude on one side and the reckless indifference to figures on the other as the basest trash, and take from it a proof that the "science" which tolerates it is a false – instead of being an "exact" – science, and we have a proof that the Earth is not a globe.
The way our vision works makes everything converge to a single vanishing point on the flat horizon, including airplanes and the sun. Artists understand this. Airplanes appear to drop below the horizon when in reality they are flying level to the flat earth and never dip their noses down to account for any supposed curve. It's the same with the sun. It is moving across the sky on a flat circular path but it appears to rise and fall due to perspective.
If we take a trip down the Chesapeake Bay, in the day-time, we may see for ourselves the utter fallacy of the idea that when a vessel appears "hull down," as it is called, it is because the hull is "behind the water:" for, vessels, have been seen, and may often be seen - again, presenting the appearance spoken of, and away - far away - beyond those vessels, and, at the same moment, the level shore line, with its accompanying complement of tall trees towering up, in perspective, over the heads of the "hull-down" ships! Since, then, the idea will not stand its ground when the facts rise up against it, and it is a piece of the popular theory, the theory is a contemptible piece of business, and we may easily wring from it a proof that Earth is not a globe.
The most commonly accepted explanation of this is that the space agencies of the world are involved in a conspiracy faking space travel and exploration. This likely began during the Cold War's 'Space Race', in which the USSR and USA were obsessed with beating each other into space to the point that each faked their accomplishments in an attempt to keep pace with the other's supposed achievements. Since the end of the Cold War, however, the conspiracy is most likely motivated by greed rather than political gains, and using only some of their funding to continue to fake space travel saves a lot of money to embezzle for themselves.