Three tributes: First, the "M" on the wall of the jail cell is reminscent of the "M" on the wall in Mary Richards's apartment. Second, Mary "that took spunk," Elka "thank you," Mary "I hate spunk" pays tribute to a conversation Mary Richards had with Lou Grant. And third, when Elka says "let's not wait another 33 years to do this again," she is referencing the fact that the MTM show's last episode aired 33 years ago.
Elka (Betty White) tells Diane (Mary Tyler Moore), "let's not wait another 33 years to do this again." It's a reference to the fact that the MTM show's last episode aired 33 years ago.