This episode is a prequel to "Rookies," a popular Season One episode that depicts Domino Squad stationed at Rishi Base. It explains the origins of the nicknames used by Hevy, Droidbait, Echo, Cutup and Fives.
The design of the clone training armor was inspired by old battered leather football gear. For those keeping track, the Domino Squad team numbering is as follows: 1. Hevy (CT-782); 2. Droidbait (CT-00-2010); 3. Echo (CT-21-0408); 4. Cutup (CT-4040) 5. Fives (CT-27-5555).
The citadel challenge ordered by Commander Colt -- version THX variable 1138 -- is a not-so-subtle entry in the long history of THX 1138 references in Star Wars.
The designs for the clone barracks dates back to concepts developed for Star Wars: Episode II Attack of the Clones, which were explored by the concept design team back in 2000, but never finished.
The script initially described Bric as human, but his design instead was inspired by the "Brainee" alien spotted in the Mos Eisley Cantina in Episode IV. Likewise, El-Les is based on the "T-Head" alien from that scene. The Expanded Universe describes these species as Siniteen (an anagram of "Einstein") and Arcona.
