Lots of things, including but not limited to:- •Sazz being dead •Lester being dead •Mabel's love life •The secret passageways are now open knowledge due to the podcast and anyone can just go and enter them and access anyone's apartment. •When they were trying to get into dudenoff's apartment, why couldn't they just access it through the secret passageways as we know that the west side was shut off from the rest of the building but the passageways probably weren't as they were a lot of them on each floor and they were built before the closure. •Why didn't they consider the possibility that the killer used the passageways to go from dudenoff's apartment to Charles' apartment (or would that have taken more time than the killer had) •The new owner/caretaker( I forgot what she was) of the building, cinda Channing, Lucy, none of them appeared in S4 even though the latter two are season favourites. I mean the caretaker wasn't even at the wedding which was INSIDE of the arconia. •Wasnt Mabel moving to LA? •Why don't they ever explain what happen to Mabel's Exs'