So you're saying that they went to the moon... which, according to flat earthers, is somewhere in the atmosphere (in which case anyone could reach it by just using a plane, but putting that aside), they were able to somehow jump around in 1/6th of earth's gravity on the moon (even though, according to flat earthers, gravity doesn't exist, and the only reason things fall to the ground is because they are denser than their surroundings, except that the sun and the moon don't fall for some reason...) and they then used the 1960s version of photoshop to paste a round earth in the sky, after removing the flat earth which would have covered the entire sky, and this was all to serve this omnipotent conspiracy that the USA and USSR were totally working together on.
...makes perfect sense.