Disenchantment can't seem to make up its mind about whether the world is round or flat. Chapter VIII: The Limits of Immortality and Chapter XXVII: Bad Moon Rising both feature the Edge of the World, suggesting that the world is flat. Also, in Chapter XI: The Disenchantress, Jerry points to a portrait and says, "This loon thought the world was round". And in Chapter XIX: The Electric Princess, after Sky says, "science makes the world go round", Sorcerio replies, "What the world and round have to do with one another I'll never know". Both of these point to the majority of characters knowing the world to be flat.
However, a globe seen in Odval's chamber in many episodes, is round. A globe, which is meant to depict the world, which up until here we've discussed is flat, is round. And after Alva leaves the world in a rocketship in Chapter L: Goodbye Bean, one can see that the planet he leaves is round, not flat.
Also, let's talk about Miss Moonpence. She's always seen hiding behind Odval's walls, and the thing we see most often is her eye. In Chapter L: Goodbye Bean, she finally has a face reveal, revealing her to be a pig, however, this contradicts Chapter XIX: The Electric Princess and Chapter XX: Tiabeanie Falls, which show her having a human ear and human hand. Maybe she was turned into a pig somehow in the thirty chapters that follow, but there was no way to explicitly show that as Miss Moonpence's face is always concealed.