Raj has no lines in this episode. He only appeared in one scene, and as Penny and Beverly were in the room, he did not get a chance to talk. However, he does whisper in Howard's ear to communicate.
In the beginning of this episode Penny (Kaley Cuoco), Leonard (Johnny Galecki) and Sheldon (Jim Parsons) are watching How the Grinch Stole Christmas! (1966). Christine Baranski, who plays Leonards mother, stars in the live action How the Grinch Stole Christmas (2000).
This is the first of two episodes where a main character only appears in a non-speaking cameo, the second one being episode 9.7, The Spock Resonance (2015).
Sheldon mentions the professional rivalry between scientists Isaac Newton (1642-1727) and Gottfried Wilhelm Leibniz (1646-1716) over their creation of calculus. Newton and Leibniz concurrently developed "infinitesimal calculus" ("the calculus of infinitesimals") in the late 17th century, while working independently of each other. Newton accused Leibniz of plagiarism, causing a long-term dispute between them.
Sheldon says that he would like to "depart[...] the starship Enterprise in a one-man shuttlecraft, headed to the planet I rule, known as Sheldon Alpha 5". He is referring to 'Ceti Alpha 5', the planet on which Captain Kirk's nemesis Khan was famously exiled in Star Trek II: The Wrath of Khan (1982). Sheldon often refers to this movie and Khan, even quoting entire lines in The Creepy Candy Coating Corollary (2009).