Don't know nothing about nothing when it comes to curvature, or gravity for that matter. I see and hear some decent argument's from the flat Earth guy's that make me think, and I like that.

On a flat plain the stars, in what's considered the southern hemisphere would be the same as the North.

Since I have never been to the southern hemisphere I can not verify this for my self. However based on a spherical model there are going to be stars seen from the southern hemisphere that people in the northern hemisphere never see, and vise versa. Is this the case? Or is the sky in Canada exactly the same as in Australia?

People have stated that the view of the moon from the southern hemisphere would be inverted compared to the Northern hemisphere. On a flat plain the moon would look the same, from the great white north of Canada to the southern most tip of Melbourne Australia(or would it be northern most tip). Again since I have never been south of the equator I personally can not verify if this is so. However it is a theory that could easily be tested by people who travel.

Flat Earth theory has serious doubt's about rotation of the Earth. Which is easily debunked. When on a train moving at 90mph for arguments sake everything in the train is also moving at 90mph therefore we don't feel the motion, if you jump in a train you land in exactly the same spot, for the most part. The tracks are not perfectly flat, the speed is not perfectly constant and crosswinds and a multitude of other factors contribute to shaking and bumping etc. However under perfect conditions black out the window's so the people inside could not see out and they would believe they were in a stationary room not on a moving train. Unless the train came to a sudden stop in which case the inside would get a new paint job.

As for why the stars are nor rotating around at dizzying speed's I believe the same principal applies. If the Earth is spinning, and the stars are also rotating motion would not be detectable. In fact the galaxy around us would have to be moving at a greater speed than the Earth it self otherwise yes we would wizz right past them and they would leave streaks in the sky. However I wont hold to tightly to that because that stuff is way above my pay grade.

Flat Earth requires a massive ice mountain to essentially circumnavigate the plain. Not impossible.

Now here is the tricky part. Convincing everyone that a flat plain was round would take a massive conspiracy listing the people who would need to be bribed, bought off or killed etc would be an exceptionally long list.

The only way I could see this as being possible is with magic(science we have no explanation for atm)

The movie Jupiter rising had a little league of alien's that went around wiping peoples memories on a massive scale when thing's went side ways. Men in black also had technology that could mess with memory.

And to a lesser degree in the Fable Haven books there was a form of magic that sort of distracted people from venturing to where they were not wanted. for example a spell could be put on a gate and people would automatically walk past the gate and never retain any memory of the gate's existence.

To that end I would ask why the flat Earth people were not bribed bought of killed or had their memories tampered with?

Finally I have to ask why no one has simply sent up a rocket with a go pro and taken picture of the flat plain for them selves. The technology is commercially available today. You might not be able to go over to wall mart and grab it and there may be cost restriction's to some, but I bet it would be cheaper than flying to Melbourne to see if the moon was upside down.