#3 seems existentially hard to prove- and it seems like half the competition would be getting cold, hard evidence that they did it- recording themselves doing whatever at a much higher resolution than possible might work.
#4 Makes sense. Maybe the earth is actually flat, and they got to the other side of it? [/s, obviously]
2) are the authors of /r/outside beta-testing a new faction?
3) are humans from the future messing around, then looking up incidents in history books and competing with each other who made a bigger splash?
4) is there a group of humans with so much advanced technology and science that the rest of us are just neanderthals in comparison?