The chinchillas singing Handel’s Messiah were originally mice singing La Traviata. Mike thought that was directly from the movie Babe, which I never saw. It’s possible it bubbled into my brain subconsciously.
Abe Vigoda singing “Oops I Did It Again” was one of the replacements for that line which floated around in discussion. The debate was spirited, but I went with something close to my original intent. It’s not hard to imagine the chinchillas.