Was this made into a time travel comedy to cash in on the success of Back to the Future?
Besides coming out roughly a year and half later, it's awfully coincidental that Christopher Lloyd was not only in Back to the Future, but in the previous Star Trek movie.
I've always heard that Leonard Nimoy was pretty much given creative carte blanche on The Voyage Home after The Search for Spock had to tie-in more closely to the events in The Wrath of Khan. I wonder if there was any other way to tell an environmental message outside of the context of time traveling back circa 1986 San Francisco?