Salam Alaikum,
The Quranic hints that are leaning towards a flat earth theory:
1 - In the Quran the sun, moon and stars are somehow grouped together as being "between" heavens and earth. Heaven and earth are complimentary and in one category (38:66), while they are not treated as heavenly objects, such as sun, moon and stars. (ex. 7:3, 22:18)
2. If Sun and Stars are the same thing, then why would Allah make a Chapter called Chapter / Sura of the Sun and a separate one called Sura of the Star?
3. According to the Quran heavenly bodies such as Sun, Moon and Stars are mobile and moving, while the heavens and earth are never explained this way. The Sun, Moon and Stars are described as running, floating, rising and declining for instance. Earth and heaven not. (ex. 14:33, 18:86, 18:90, 31:29)
4. Earth was created before the 7 heavens (2:29), and what is interesting is that the "lamps" that are commonly understood as heavenly bodies such as stars are supposedly only present in the most earthly level of heaven, also known as the first layer out of 7. (67:5, 41:12). The sun, moon and stars are clearly described as being in the heavens and earth (ex. 22:18)
5. Then there is that description, actually descriptions that show us that Allah uses terms that can only be understood with flat, non-spherical shapes:
earth spread (ex 13:3)
earth spread Arabic term #2 (ex 51:48)
earth spread Arabic term #3 (ex 71:19)
regardless of the countless translators of these words, they are always either related to spreading, or more resonating with horizontal 'like carpet' expansion.
6. The mountains are described as stabilizers, or pegs that stop the earth from shaking. (ex 31:10) To me personally i see this not applicable on a spherical earth, as those pegs would not really stop it from moving, other than let's say a carpet.
7. Interesting analysis of Quran verses concerning earth. The Jannah or promised paradise is said to be the same size as heavens and earth (3:133). And the heavens and earth are said to become replaced with a new heavens and earth (14:49). To me it means that Paradise will be simply a replaced heavens and earth, or an improved one. And at that time, we will have the whole of creations as our playground in peace and harmony. in sha Allah. And that means that the resurrection is in the same location as here, with a renewed earth (30:25). There is no indication that there are two parallel earths somewhere from the quran anyway. Correct me if i'm wrong.
8. Also notice that every time Allah mentions Heavens and earth, we have earth singular and heavens plural. There is no talk about earths. And again, as mentioned before, according to Quran the earth was created before the 7 heavens (2:29).
From the above we can conclude that the way all translators of the world understand and interpret the Quran, we have earth as not spherical, rather immobile, while heavenly bodies such as Moon, Sun and stars are moving and "between" the heavens and earth.
We can be sure (unless you prove me wrong, which i would appreciate), that in the Quran there is no evidence of a round world, but quite the opposite. Nor that the sun and stars are the same thing. Or that we are a tiny little ball that is going around a medium sized sun/star, which is one of 70 trillion stars in a galaxy of 70 trillion galaxies of a universe. Rather, there is only talk of one earth, that is spread out and vast, that will one day be crushed and replaced. And that we will be resurrected here on that new earth, under a new heavens.
Please, if you have any hadiths about this let me know
Fi Aman ilah