Plot hole: In some episodes Lucy can not sing at all. In other episodes she can sing.
Other mistake: In some episode Ethel can play the piano and in others she cant.
Continuity mistake: In season 3, "Lucy and Ethel Buy the Same Dress", when Ethel comes out of her bedroom wearing the dress she had told Lucy she'd return, Fred calls her "Ethel Louise." In season 3, "The Million Dollar Idea", when Ricky tells Lucy and Ethel that it will cost them twenty cents to mail each dressing jar, Lucy takes Ethel by the hand and calls her "Ethel Roberta." In season 4, "Ethel's Hometown", throughout the episode Ethel is called "Ethel Mae."
Continuity mistake: At times Ricky wears his gold wedding band, and other times - especially at the Tropicana - it is missing from his finger.
Suggested correction: So he took it off while performing. I googled images of Desi and Lucy and you can see he wore a wedding band in real life. Therefore, taking it off while filming would have been a deliberate choice. It's only a mistake if the band appears and disappears within a scene.
