First appearance of Clone Sergeant Appo, who will end up commanding the 501st Legion during the Order 66 march on the Jedi Temple in Star Wars: Episode III - Revenge of the Sith (2005) (although his name is never mentioned in the film). The arrow shape on his helmet (which is not on it in Revenge of the Sith) is a nod to the character Appa from Avatar: The Last Airbender (2005), a series on which supervising director Dave Filoni previously worked. And who was also voiced by Dee Bradley Baker
About midway through the episode Hardcase says "I prefer a good fight to all this sneaking around". This is similar to Han Solo's line in A New Hope where he says "Well bring em on! I prefer a standup fight to all this sneaking around."
The 2020 anthology book "Star Wars The Clone Wars: Stories of Light and Dark" features a story based on all four parts of the Umbara arc that is told from Rex's point of view. It is written by Yoon Ha Lee and titled "The Shadow of Umbara". The audio-book version is read by Clone Wars voice actor James Arnold Taylor.
The 'Jedi fortune cookie' message that opens the show reads "The path of ignorance is guided by fear."