The fifth episode of the Star Wars: The Clone Wars television series, entitled "Rookies," is part of Season One. As the fifth episode overall, it was initially broadcast on Cartoon Network on October 24 of 2008. Later, it was broadcast on TNT, with its premiere occurring on February 25 of 2009.
A small squad of rookie clones is stationed on the isolated Rishi Moon, including Hevy, Echo, Fives, Droidbait, and Cutup, and they are bored and eager for combat. Echo is occupied with studying reg manuals, while Hevy is lost in daydreams of fighting on the front lines. Sergeant O'Niner reminds them that their listening post is crucial for monitoring Separatist movements and preventing a surprise assault on Kamino, the planet responsible for clone production and training. The Sergeant instructs his troops to get ready for an inspection by Commander Cody and Captain Rex, who are on their way. Soon after, the station's sensors detect an approaching meteor shower, triggering the automatic raising of its shields. However, not all of the meteors are natural; two of them are actually boarding ships carrying a number of droid commandos.
The droids quickly get into the base and waste no time in killing Sergeant O'Niner and three rookie clone troopers. This forces the four remaining clones to escape through the exhaust vent. The commando droids then report their success to General Grievous. Delighted, Grievous gets in touch with Asajj Ventress on Kamino, where she is secretly arranging a Separatist invasion.
Hevy, Echo, Fives, and Cutup emerge from a maintenance tunnel into a deep crater beneath the outpost and start planning what to do next. Suddenly, a huge Rishi eel silently appears from one of the many caves in the crater, grabs Cutup in its mouth, and retreats back into its cave, surprising the other rookies. At that moment, Cody and Rex's shuttle arrives for a landing above them. Hevy, Fives, and Echo are unable to communicate via radio, so they decide to use a warning flare.
Up on the platform, the clone officers are greeted by a strange "clone" who moves awkwardly and speaks like a droid. The "clone" attempts to reassure them that the base is in perfect order, but Rex insists on seeing the sergeant in charge. When the "clone" replies with "Roger, roger," the officers immediately grow suspicious, and then Rex notices the flare. Rex instantly shoots the impersonator, surprising Cody. Rex tells Cody to relax, and then removes the helmet, revealing a droid commando underneath. The remaining commando droids quickly ambush the two officers; in the resulting battle, they manage to destroy one of the droids before the captain and another droid throw thermal detonators, destroying their ship. Rex and Cody use the explosion as cover to escape into the crater, where they encounter the rookie clones. Rex, unsure if they are droids, demands that they remove their helmets. They comply, reassuring Rex. The eel returns for another attack, but Rex kills it before it can strike. The two officers then explain to the rookies that they need to reclaim the base with the "shinies." Rex and Cody are committed to retaking the base, and Hevy, Fives, and Echo are ready to join them.
Because they don't have the weapons needed to breach the blast doors, Rex devises a plan. He disguises himself as a droid commando and approaches the gate, where three commando droids are standing guard. Unit 07 responds and notices that Unit 26's vocabulator is malfunctioning, so he demands to see his faceplate. Rex dives down and picks up Unit 26's droid head. Cody remarks on the absurdity of the plan, but Unit 07 falls for the trick and opens the gate. The three commando droids are taken by surprise by Rex's appearance and are shot down by the group. They then storm the command center and recapture it from the commando droids.
Unfortunately, the Confederacy navy led by Grievous has arrived, and when he is unable to contact the commandos, he sends in reinforcements. Determined to prevent the base from falling back into enemy hands, the clones decide to destroy it using liquid tibanna, which would disrupt the all-clear signal, thereby alerting the Republic. As the other clones escape through the tunnels, Hevy attempts to arm the explosives, but the remote fails to work, so he decides to activate it manually. In a heroic final act, Hevy is wounded. The droids are unsure of what to do with him, questioning whether they take prisoners; Hevy defiantly states that he does not, and triggers the explosives. The base, along with Hevy, is destroyed. Alerted, the Republic fleet jumps into the system, forcing Grievous to retreat due to being outgunned.
Upon their return to the Resolute, Echo and Fives are awarded medals and Rex welcomes them into the 501st Legion. The rookies feel undeserving of the honor, but Rex assures them that they have earned it.
During the initial broadcasts of this episode on Cartoon Network, the word "Hell" was used as an expletive on two occasions. However, during the replay on November 7 of 2008, before "Downfall of a Droid" was shown, the word was censored because of complaints from parents. In Canada, neither CTV nor the Space network censored it, although the series has a 14A rating in Canada, which is similar to PG-13. The word was not censored during its broadcasts on TNT. However, in the iTunes version, it was censored only once. The episode is uncensored on Disney+.
When the droid impersonating Sergeant O'Niner tries to persuade Cody that an inspection is unnecessary, it imitates Han Solo's lines "We're all fine here now, thank you" from A New Hope.
On the screen of the detonator used by Hevy to destroy the base, the words "ATTE RUL3Z SOME TEXT" can be seen written in Aurebesh.
Almost two years after "Rookies" was originally broadcast, a prequel episode and a sequel episode were shown on Cartoon Network as the premiere of the third season on September 17, 2010.
In the scene where Rex removes the helmet of the disguised commando droid he just destroyed, and he and Cody are subsequently attacked, the piece of Cody's armor that should be on his right thigh is missing.
When Rex is fighting the commando droid captain, he has a pistol in his left holster even though the clones only had enough blasters between them that Rex had to loan his other pistol to Cody so everyone would be armed.
When Fives and Echo are awarded their medals, the camera is behind Echo is just holding his hand out without a helmet, which only appears in a shot from in front of him. He's also seen without his binocs, but on the second scene he is seen with the binocs on his helmet.