While sitting in the hot tub, Frasier explains that it is "made from the same heat-resistant space age polymer that's used on the NASA space shuttles". The heat-resistant surface of the space shuttles was principally made from ceramic tiles, not a polymer.
Roz corrects Frasier when he says "a yen for Chinese food", telling him that "yen" is Japanese. While the yen is the currency of Japan, the English word "yen" (meaning "a desire for") is actually Chinese in origin.