I've gotten 29.... i see people saying 30 here but i really can't find the 30th at all. I got the purple question one earlier on, 29th one i picked up was the falling platform one. I feel like i might be missing something very obvious.
Was a cassette level inside some door that didn't open for me before. I knew it looked like something should be behind there but didn't try everything to open it each time i was close.