Louis Gossett Jr. said in a television interview that he had talked while gargling saliva as a kid as one of those kid things. He told Wolfgang Petersen that he thought that it would add a good touch to his character. Gossett performed the odd vocalizations all by himself (no mouth prosthetics or post-production effects), and often does "the Drac voice" at convention appearances.
According to Louis Gossett, Jr., the Drac language was created from scratch. Much of it was Russian, pronounced in reverse.
Author Barry Longyear reported at a convention that the studio insisted on adding a subplot involving a mine, thinking the audience would not realize that the "Mine" in the title was a possessive (as in "My Enemy") rather than an object.
The outside scenes (all the volcanic/lava landscapes and the green lake) were shot in Lanzarote (one of the Canary Islands off the coast of Morocco), at the Montañas del Fuego National Park. The rest was filmed at the Bavaria Film Studios, Munich, West Germany. A few of the sets are still part of their studio tour.