Big Bang #0 marked the end of an era, in more ways than one. It was the third part of our Golden Age trilogy which introduced the 1930s and 40s versions of the characters. On the other hand, it was pretty much our farewell to Caliber Comics as we would soon be moving Big Bang to Image Comics.
Caliber had already published BB issues 1 through 4, Berzerker 1 through 6, Knight Watchman #s 1 and 2, the Dr. Weird Special and Dr. Weird #s 1 and 2. (More on those comics in the next BANG! or two).