The Camera Eye - an oscillating LFO synth sound (sample and hold) at the beginning of the song
La Villa Strangiato - when the guitar bursts out (2:00) and Geddy's awesome bass solo (6:11 - 6:14)
Turn The Page - intro bassline and the warm synth sound (0:39 - 0:40)
Middletown Dreams - part right after Alex's guitar solo (3:12)
Between The Wheels - PPG bell synth sound in choruses
Synth solos on Countdown and Subdivisions
...And of course, etc.