By that I mean, if you are travelling about on a continent on a planet with a circumference similar to the Sun, how much further would you be able to see, and would it be noticeable, without more complex scientific instruments? Would standing on a mountaintop, or the shoreline of a Atlantic ocean sized body make it noticeable enough?
Most other challenges (Gravity for one) of a planet with that size and mass are fixed or handwaved by a number of other things, but for the sake of argument you just wake up in a coniferous filled woodland, and as you wander, you find hills, plains and mountains, lakes and oceans, with pretty much the same array of features, and the same range in terms of height and depth, as on earth.
--Crazy background follows-- Feel free to ignore if this complicates the answer too much. I'm mostly interested in the geometry, but the TL;DR is, math is still the same, space doesn't bend in weird ways, and neither does light, but throw out pretty much most of what you know about astronomy.
This is for a very much magical world where people from our normal earth were brought. Continent sized 'floating' islands are in a orbit of sorts around a star-like central object after fracturing eons ago, with their surface pointed away. Even before the fracture and the dispersal of the 'islands', the planet was the size of the sun (Or just very very big). So would someone from Earth be able to easily notice this difference? Most knowledge regarding astronomy, save the math, is useless in this world (No stars; the "sun" at the center of the islands provides 'sunlight' by reflecting it unto a moon like object that disperses it onto some of the islands some of the time. The glittering lights in the night sky are the crystallized (frozen over?) remains of the planet that did not settle into continents