19. Let That Be Your Last Battle
Visual effects supervisor Ken Ralston hated the Enterprise model. He hated it so much, in fact, that he was looking forward to taking a mallet to the $150,000 model. While the studio was having absolutely none of that, they did need to show the Enterprise exploding in space.
Using the exact same self-destruct code that had been used in the Original Series episode Let That Be Your Last Battlefield, the ship is set to auto-destruct by Kirk. To achieve this, several shots were layered, one atop the other. The first centered on the bridge itself.
A separate bridge module was constructed and filmed in front of a starfield background. Then, the shot goes wide and shows the Bird-of-Prey moving out of harm's way. This was filmed upside down, giving the effect of absent gravity.
For the shot of the fires melting the registration number on the saucer section, Ralston had a styrofoam saucer created, then melted sections using acetone, dripped down at various intervals.
Finally, for the big explosion, a much smaller model was constructed, allowing the crew to destroy the old girl. All in all, this very short yet important scene in the film was technically a massively complex achievement by Ralston and the team at ILM.