Rei's horrific vision of the future is the one lingering reminder of the seriousness of the S season. Every few episodes, despite whatever daily villian Sailormoon fights, the viewer is presented with Rei's vision of destruction, death and despair. However, despite seeing these images, Rei chooses to stay silent on the subject. It is not until Setsuna shows Usagi this vision do the girls finally understand what they're up against.

Rei's disturbing vision is the last example of her telepathic abilities that was presented in this anime. After this season, Rei never speaks of her premonition abilities. It is as if, shocked by her vision during this season and the destruction that arose from it, she has chosen to ignore this ability. That might possibly explain why Rei's character becomes less concerned with her duties as a shinto priestess and more with making money in the adult world. The S season, in effect, marks the end of Rei's character growth and her readiness to enter the adult world.

From Episode 119 - "Chimmoku no Messiah Kakusei? Ummei no Hoshiboshi"(Messiah of Silence's Awakening? A Fate in the Stars).