looks like there's space for three LEDs that they didn't end up using. The top shell has space for plastic light pipes above them but they don't go through the shell
"Aside from working with Rez, the Trance Vibrator also works with Space Channel 5: Part 2 and Disaster Report (known as Zettai Zetsumei Toshi in Japan)."
Disaster Report support is some galaxy brain shit
uploaded a scan of the manual to archive.org in case anyone wants to read it https://archive.org/details/trance-vibrator-manual