This is the first time I can recall seeing Diane and she actually having lines in a scene. If I remember correctly, Rick was working on portal travel and was stuck, she encouraged him, and there was a comment about someone going for ice cream when Rick Prime dropped the bomb which killed Diane.
I can't recall an explanation ever given as to why Rick Prime first killed C-137's Diane and then used the Omega device to erase Diane from all dimensions. One theory I heard once was Rick Prime was the first to discover portal travel, choose to explore the dimensions versus staying with Diane and Beth, Diane left him with Beth and the pain was so profound that he wanted to erase any memory of Diane.
Overall, liked the first 20+ minutes of this one, thought it fell apart a bit at the end of the chase scene, and liked the ending. Reconfirmed Rick has always been a shit father, Diane is the parent who raised Beth, and when Diane was killed C-137 was unable to put aside his pain and loss for the good of their daughter. That story line is pretty damn real for far too many families.