The on-hold music, "Feels So Good" by Chuck Mangione, is the same tune Sheldon plays on a flugelhorn in his dream in "The Relaxation Integration."
First physical appearance of Raj's mother in the series.
Sheldon again mentions the failure of Howard's space toilet, the Wolowitz Zero-Gravity Waste Disposal System seen in The Classified Materials Turbulence (2009). At the time, Howard blamed its failure on a small mistake he made with the diverter valve, but now he claims it was due to "Russian cosmonauts and their potato-based diet".