>>10697093The one idea that Marcia Lucas specifically contributed to the final cut was giving the Rebels 15 minutes to destroy the Death Star before it opened fire on Yavin IV, because that wasn't in the original script. You can tell that all of this exposition is delivered by PA announcements that were dubbed in afterwards and tactical displays that were added in post. Tarkin saying "You may fire when ready" and the gunners operating the controls were reused from the destruction of Alderaan.
