20 Things You Didn't Know About Star Trek III: The Search For Spock (1984)
13. When In Doubt, Fill It With Smoke
Filming the interior of Spacedock was a process that took months to complete. Effects cameraman Scott Farrar decided that to film inside, and make it look convincing, they needed to add a degree of atmospheric haze. He admitted that there probably wouldn't be anything like that in space, but needs won out.
The crew used blue colour gels to give the distinctive hue, while they blew smoke into the set and filmed through it - all to give it a more worn-out, lived-in look.
One of the greatest on-screen tricks that the film pulls is to show the Excelsior and the Enterprise both in Spacedock at the same time.This was a physical impossibility for several reasons.
To get around the logistical issues, both ships were filmed separately and then composited into the scene together. To give the entire sequence a grounded feel, the cafeteria shot was added. This is best noticed in the scene as the Enterprise arrives. Filmed on the ILM soundstage, the set was filled with 40 extras - and Grace Lee Whitney, returning to Star Trek after her appearance in the Motion Picture, though credited here as 'Woman In Cafeteria'. It is she who reacts to the ugly scars along the Enterprise's hull.