In several pieces like this I read that "Bruno was not an astronomer and demonstrated a very poor grasp of the subject in what he did write" and that "It is in his Ash Wednesday Supper that we find Bruno's fullest expression of his version of Copernicus, and this work reveals that much of what he knew appears to be second hand, and is incorrect or at least confused in particular astronomical details".
Can you give some examples of his mistakes about astronomical details?
If you don't get a lot of good stuff here, you could always try /r/askscience as well.
Francis A. Yates argues in "Giordano Bruno and the Hermetic Tradition" that Bruno was heavily influenced by Ficino's De vita coelitus comparanda, leading him to "patronise Copernicus for having understood his theory only as a mathematician, whereas he (Bruno) has seen its more profound religious and magical meanings." Yates also claims that "Bruno pushes Copernicus' scientific work back into a prescientific stage, back into Hermetism, interpreting the Copemican diagram as a hieroglyph of divine mysteries."