Taking its cue from the "mask" scene in "Communion," "Fire in the Sky" suggests that the big-eyed "Gray" visage (already a consumer touchstone by the film's release in 1993) is due to the metallic "spacesuits" worn by the aliens, presumably for excursions outside their vehicle.
The alien sequence is replete with arresting detail, from the UFO's eroded, labyrinthine interior to the bits and pieces of debris Walton rakes up with his hands as he's dragged down a dimly lit corridor to the aliens' laboratory. The alien environment's thoroughly aged appearance subverts the conventional image of ET spaceships as pristine and clinical. Instead of the pragmatic decor and sourceless lighting reported by abductees, we're treated to what amounts to a space-borne catacomb. Even the aliens defy the expected "Grays" in critical respects; their necks, for instance, feature a detached "extra" throat that cleverly accentuates their mummified physique.
Verisimilitude notwithstanding, "Fire in the Sky" articulates powerful fears of what the abduction phenomenon represents. Perhaps its most striking contribution to the canon of UFO-themed movies is its insinuation that the aliens behave so strangely not because they're evil so much as amnesiac, their original agenda so faded with time that their very spacecraft has begun to decay. For all their technological might, they're a species on the brink of dissolution, sustained by inexplicable sadistic impulses.
More importantly, the cosmic molesters of "Fire in the Sky" serve as frightening caricatures of what human science might become under the unmitigated burden of postindustrial society. We expect our galactic elders to be wise, even compassionate. "Fire in the Sky," and the beings it attempts to represent, are a mocking reminder that such assumptions may be rooted in our own implicit, unexamined desires.