One interesting tidbit is that Aranea actually discusses the foreshadows not just the retcon but also the exact circumstances it which it would be used (Terezi getting John to F1X TH1S by saving Vriska) all the way back in Act 6 Intermission 2. I am too lazy to go into all the depth of the topic but go reread page 4771 with both the retcon and the philosophy of candy John.