Talk:My Little Pony Equestria Girls: Forgotten Friendship/@comment-26434885-20180218015028/@comment-25559529-20180218034806

Wallflower didn't think to erase Sunset's memories. That wasn't her plan.

Also, Trixie's were erased as well, but Sunset talking about the Memory Stone made her realize what was going on. She knows she wasn't faking it due to Sunset's realization that Trixie had no idea what she was talking about.

It's hard to imagine that Trixie could judge a conversation like that, but there you go.