When Christine McIntyre, as "Alice", is singing "The Voices of Spring" in the radio studio as the film opens, that actually is McIntyre's voice you hear--she was a trained opera singer and had a beautiful soprano voice.
The mock operatic recital performed by Señorita Cucaracha, Señor Mucho and Señor Gusto, is "Chi mi frena in tal momento" (the Lucia Sextet) from Act II of "Lucia di Lammermoor", a dramma tragico (tragic opera) in three acts by Gaetano Donizetti. It premiered on 9/26/1835 at the Teatro San Carlo in Naples, Italy.
Radio call letters KGBY were used from 1926-28 in Shelby and Columbus NE, and then again from 1991-2011 in Sacramento, CA.
The song Alice sings is "Voices of Spring" by Johann Strauss Jr., often performed as part of his opera "Die Fledermaus".
The song Signor Spumoni is attempting to sing when the boys toss cherries into his mouth is an excerpt from the Italian light aerie "Vieni Sul Mar."