Desi Arnaz Jr. Is not listed as a credited actor in this episode.
While the characters were talking about a "fake" Guarrneri, the "real" one was Bartolomeo Giuseppe Guarneri 'del Gesù' (1698 - 1744). Guarneri made just 150 violins, and the auction record for one of them is $9,440,000, sold in March 2023.
The title refers to the musicians in the employ of the childhood nursery rhyme character Old King Cole.