The scene where where Selina walks through a glass door is based on the same real-life accident incurred by the show's creator Armando Iannucci. Filming the tricky scene involved using tempered glass, Plexiglass, and crew members dropping fake rubber glass from above onto Julia Louis-Dreyfus.
Julia Louis-Dreyfus says she ad libbed the line--playing Selina in the scene where she's heavily doped up--about suddenly being delighted to discover she can say Jonah's name backwards: "Hanoj".
Matt Walsh (Mike McLintock), Sam Richardson (Richard Splett), and Randall Park (Danny Chung) also worked together on Office Christmas Party (2016) as Ezra, Joel & Fred respectively.