The Holographic Excitation is the 5th episode of the 6th season of The Big Bang Theory.Raj plans Stuart's Halloween party at the comic book store, Howard annoys the rest of the gang by constantly talking about space, and Penny tries to take more of an interest in Leonard's work with surprising results.
- Actor Allusion: One of the couples costumes Amy suggests is Blossom and Joey. Mayim Bialik, who plays Amy, also played Blossom.
- Adam Westing: Astronaut Buzz Aldrin appears in The Stinger, bragging about walking on the moon (as Howard had been bragging about being an astronaut) to some trick-or-treaters.
- Coordinated Clothes: Howard and Bernadette go as Papa Smurf and Smurfette. Amy wants Sheldon and her to also have a couples costume, but can't agree between Raggedy Ann and Andy or R2-D2 and C-3PO. They compromisenote and go as Raggedy Ann and Raggedy C-3PO.
- Geeky Turn-On: Leonard's speech regarding string theory really turns Penny on and reinvigorates her passion for him.
- Halloween Episode: The Halloween party is the main setting for the episode ending and drives much of the plot.
- Have You Come to Gloat?: Everyone's response toward Howard's constant gloating, he gets better by the end.
- Informed Attribute: Raj talent for party planning, turns out he really can plan a great party.
- Sex Equals Love: Leonard and Penny have sex twice in his lab and then in the Tardis during Stuart's Halloween party.
- Sexy Whatever Outfit: Penny dresses as a sexy cop. She notes that slutty cop was just a skirt and two badges.
- Raj rents a TARDIS photo booth.
- Among the couples suggested by Amy and Sheldon for a couples costume are Lady and the Tramp, Kirk and Spock, Romeo and Juliet, Arthur Dent and Ford Perfect, Jack and Rose, and Dharma & Greg (the last one an allusion to another Chuck Lorre-created show).
- Stuart is dressed as Willie Wonka at the Halloween party.
- Wham Episode: After being confused over her feelings since the start of the Season, Penny rediscovers her passion for Leonard.