Anu's U.S. Constitution costume featured the Bill of Rights on the back, which the costume designer researched at the National Archives website to ensure accuracy.
Leonard is shocked when Penny claims their first kiss was at his birthday party. Leonard correctly recalls it happening at a Halloween party (Season 1, Episode 6, "The Middle Earth Paradigm") where Penny was drunk and upset over her ex, Kurt. Penny later admits she remembers but prefers the birthday memory because it actually meant something to her. [S12E6] The Imitation Perturbation
Howard arrives at work dressed as Sheldon, mimicking his "spot" and bathroom schedule. Hurt by the ridicule, Sheldon and Amy retaliate at Leonard and Penny’s party by dressing as Howard and Bernadette. Amy’s "spot-on" high-pitched impression of Bernadette is a highlight, though it causes genuine friction between the couples. Anu's U
The episode concludes with a touching, intimate moment between Sheldon and Bernadette. They bond over shared childhood experiences of being bullied for their small stature. Notable Costumes Howard Sheldon Cooper (later Bert from Mary Poppins ) Sheldon Doc Brown (later Howard Wolowitz) Amy Clara Clayton (later Bernadette) Leonard Inspector Gadget Raj "Kooth" Bader Ginsburg Anu The U.S. Constitution Bernadette Mary Poppins Leonard correctly recalls it happening at a Halloween