Milton Burke was originally asked to emcee the PTA benefit, and agreed to that role. However, in the final scene, he's participating in a full skit with lines and a song that he would have had no time to learn considering he spent the days leading up to the benefit working on his book and then goes straight from the office to the benefit.
Milton Burle questions Ricky being Latin with a last name like McGillicuddy and Lucy says it's "Irish Latin." However, in "I Love Lucy," specifically in "Lucy Goes to Scotland" we learn Lucy's family roots and maiden name originate in Scotland, not Ireland.