Before Sgt Plout about to sing, Laverne asked Shirley, Does she remind you of anybody we know? Shirley replies Carol Burnett? Vicki Lawrence was discovered by Carol Burnett and worked together often and are known for their resemblance.
The blue dresses Lavern and Shirley wear while singing with Alvinia are the same dresses they wore when they sang with Carmine at the Pizza Bowl in Milwaukee.
The title is a quote from William Shakepseare's play MacBeth: Out, damn'd spot! out, I say!