Kaley Cuoco appears in two scenes: in one, she is filmed standing behind the bar at the Cheesecake Factory, and in the second, she sits in the gang's living room behind a table. This was to hide her broken leg due to a horseback riding accident.
Sheldon's meeting with the FBI agent in her office was filmed on the set of Sheldon's office.
Sheldon blaming former President Jimmy Carter for America not making the transfer to the metric system isn't entirely fair. A Metric Conversion Act had already been passed by Congress under Carter's predecessor Gerald Ford, but because the switch to metric was voluntary, no deadline was set and not many companies complied. Carter actually attempted to enforce the Act by implementing road signs in kilometers, but a nation-wide coalition of traditionalist detractors put a stop to this. President Ronald Reagan finally stopped any further attempts at conversion in order to reduce federal expenses.
Howard's middle name, Joel, is revealed in this episode.
This is the final time in the series that Joyce Kim is mentioned, the girl that Leonard briefly dated before she defected to North-Korea. This has been a running joke since Pilot (2007).