When Sheldon runs away from the guard shack the guard announces a code "AA-23". Princess Leia was held in detention block AA-23 of the Death Star.
Penny is an excellent ping-pong player, as Kaley Cuoco was a nationally ranked child tennis player. The entire cast often plays ping-pong during breaks in rehearsals.
On the drive Sheldon expresses concern about a possible hotel detective and Leonard mocks that with a 1930s style comment about hitting the bricks. From the late 1800s to about the 1950s, most large hotels employed house detectives who wandered around looking for thieves, prostitutes, and unmarried couples trying to rent a room together.
In the end scene of the episode, Sheldon is wearing a long colorful scarf and jumps through the door of the TARDIS. This long scarf is similar to the one worn by the 4th Doctor from Doctor Who, played by Tom Baker.
Sheldon shows a very typical fanboy reaction in this episode: throughout the show, he has always been very critical of George Lucas, e.g. stating that he prefers to watch Star Wars films and series in order of release, to "let George Lucas disappoint me in the order he intended"; when planning a Star Wars marathon, he mentions that an hour in between movies may not be enough to complain about all the shortcomings of Star Wars: Episode I - The Phantom Menace (1999); and he fears nothing more than the words "George Lucas' Director's Cut". However, at the prospect of visiting the Skywalker Ranch and possibly meeting Lucas himself, he completely geeks out and all these criticisms are instantly forgotten .