"The Forgotten Droid" is the seventeenth episode of the second season of Star Wars Rebels. It is the thirtieth episode of the series overall. It premiered on March 16, 2016. It was written by Matt Michnovetz and directed by Mel Zwyer.
Official description
When Chopper steals a replacement for his original leg, he separates from the Ghost crew and finds himself stranded on an Imperial ship. The grumpy astromech meets an inventory droid in service of the Empire, but will this new acquaintance become friend or foe?