Even though this is the 52nd episode, the Roman numerals XCII in the title stand for 92, indicating the time gap since the original series run. It has been fifty years since Jack was sent into the future.
The first episode in 13 years.
Greg Baldwin is now doing the voice work of Aku because of Mako's death in 2006. Baldwin also wound up replacing Mako on Avatar: The Last Airbender (2005) for the character of Uncle Iroh.
The episode won an Emmy Awards for Outstanding Individual in Animation - character design.