 SPOILER: In the earlier drafts of the screenplay, the Enterprises  auto destruct finished with the ships engine core exploding,  resulting in a massive matter/antimatter explosion, visible from the  planets surface. Harve Bennett (qv) later changed this to the  primary hull exploding, and the secondary being destroyed in the  planets atmosphere, reasoning that an antimatter explosion would  probably destroy the Klingon ship as well. However, a mix