The guys often refer to Star Wars plots, characters and weapons, although they like Star Trek better. Penny, who is not as sci fi fluent as her friends, often uses Star Wars as her first guess during games.
In "The Weekend Vortex", the guys are playing the Star Wars online game all weekend. Amy accidently says they are playing a Star Trek game. Penny corrects her that the guys don't like them being mixed up. Amy asks what the difference is and Penny claims that there is no difference.
In "The 21-Second Excitation", they note that they should go see Raiders of the Lost Ark before it gets changed like George Lucas keeps doing to the Star Wars pictures. Jar Jar Binks from Episodes 1 - 3 is also mimicked a couple of times during the episode with Wil Wheaton doing it once.
In "The Vegas Renormalization", Penny is playing twenty questions with Sheldon, is confused and guesses "Are you Star Wars?"
In The "Pilot", Sheldon mentions Leonard's Star Wars hair products that are in the shower which their new neighbor Penny is using.In "The Hesitation Ramification", after Penny's scene on "NCIS" is cut from her episode, Leonard finds an internet audition offer for the new Star Wars movies. Unfortunately it's for fans and not a professional audition. To make her feel better he uses a Star Wars analogy (Luke Skywalker having only one chance to destroy the Death Star), however Penny doesn't really want it. Part of Howard's Star Wars audition taping session is also shown.