Dont know if I found them all I think I did though

1. 2 people in window
2. Figure standing left to the pillar after playing disc (+ knife there after)
3. Figure in the hotel hallways
4. Backrooms secret on top floor stairs
5. After shooting the disc, blood will appear around the map. Go into the backrooms and look behind you
6. Knife at generator (dont know how to recreate might be wrong)

showtriggers_toggle makes it a bit easier to find them