User blog comment:HalointheSkye/Volume 3 Chapter 8 Teaser - Hype! Hype! Hype!/@comment-24994749-20160108044601/@comment-4010415-20160108051455

I'm pretty sure Yang has seen Raven's face before Qrow showed the photo of STRQ. She has a photo of Raven that she showed to Junior in the Yellow Trailer. Granted, that photo is taken from the side, so she may have only seen the side of Raven's face before, and her brain made up the difference in the dream.