There was no opening act that I remember. There were a couple of Looney Tunes cartoons, and then the "Leave It Eurodisco" instrumental. (This music can be heard at the tail end of the "9012Live" video.) Then the band opened with Cinema/Leave It, etc.
The stage looked like a metal grid which sloped downward toward the audience. After the main set, there was a green laser which projected the YES logo (90125 style) on the ceiling of the Coliseum. Funny thing though, it was projecting backwards. Still, the fans chanted "YES!" maniacally. Cheap laugh for a college student.