When Aku is talking to the scientists about not caring about Jack, he mentions "That was the old Aku, this is the new Aku." This could be a joke regarding Greg Baldwin replacing Mako after his death.
Highest rated episode of the series.
The episode won 2 Emmy Awards for Outstanding Individual in Animation - storyboard artist and production design.
In the entire episode, there is only about one minute of full dialogue.
Here Greg Baldwin takes over voicing Aku for Mako after his passing, something he previously also did on Avatar: The Last Airbender (2005) when he likewise took over voicing Uncle Iroh.