"The Love Spell Potential" episode brings the gang together for a game of Dungeons and Dragons, with Howard (Simon Helberg) doing a spot-on impersonation of Al Pacino. In the blooper, Helberg dials up his impression, earning laughter all around the set and a hearty round of applause.
The show never revealed Penny's (Kaley Cuoco) surname, which became a superstitious commitment for fear of jinxing the series' success. In a blooper from "The Tangible Affection Proof,” Leonard (Johnny Galecki) improvs the question, "You don't have problems? What's your last name?" A stumped Cuoco sputters, "I don't know!"
In "The Thespian Catalyst," Penny helps Sheldon hone his performing skills, which includes her having to perform the Vulcan salutation, in which she fumbles and makes a different gesture instead. The audience's laughter and Parsons' confused face cue Cuoco in on her mistake, and she quickly seeks help from a producer.