Alternately, if the radiation effects are simply hallucinations, why is the invisibility so inconsistent? Berger wasn't exposed to radiation, so why is he hallucinating little people turning invisible? How does everyone have the same hallucinations (i.e., Dan, Steve, and Mark all see the cars and people vanish at the same moment)? And why do they have coordinated hallucinations (i.e., Mark hallucinating Steve vanishing, and Steve hallucinating that he's disappeared into some limbo at the same time?). Why does Berger hallucinate the disappearance of Spindrift, but not other surrounding inanimate objects?