Certain basic components are found in all subsequent editions, such as the Biblical text itself, the masoretic notes, the Onkelos Targum and Rashi's and Ibn Ezra's commentaries. However the various publishers included additional versions, commentaries and indices, with a preference for medievals.
The very first printing of the Mikra'ot Gedolot was edited by Felix Pratensis, an apostate Jew, and Bomberg had requested an imprimatur from the Pope. Neither of these facts served to endear the book on its potential Jewish clientele, so Bomberg had to produce a brand new edition under the direction of proper Jewish editors.
The Mikra'ot Gedolot includes the entire Bible, though only the section on the Torah, the first five books, is described here.
The Masoretic notes to the Biblical text were carefully edited by Jacob ben Hayyim Ibn Adoniyahu, and established themselves as the standard version of the Masorah.