This is the last episode to feature Linda Gary as Aunt May Parker. She died not long after recording her final pieces of dialogue of brain cancer.
Kraven mentions he last met Spider-Man as friends and Spider-Man said Kraven once saved his life. Both of them are referring to Neogenic Nightmare Chapter 8: Duel of the Hunters (1995) where Spider-Man transformed into Man-Spider.
No explanation is given as to why Mariah reacted so extremely to the serum. Though a popular theory is that it has to do with hormone differences between genders.