In this episode Lucy said that today is Little Ricky's 3rd birthday, but in "Nursery School" Ricky said that Little Ricky is 3 years old.
Because William Frawley was an alcoholic, his hands would shake. You can see this during the scene where Fred is reading his mail at the hotel.
Lucy and Ricky's room number at the Hotel Grande is #47.
Ricky: She had no trouble understanding me.
Lucy: Just my luck, I'd have to get an operator in Italy who studied English in Cuba.
Fred: Ethel, you ought to see our room. There's a flock of pigeons right outside the window.
Ethel: Those aren't pigeons up there; they're angels.
(Ricky sits on a hard bed)
Ricky: Is this box springs without springs?
Ethel: One flight up? What did you give us? The bridal suite for mountain goats.
Lucy: That elevator she's a no bust; she's a pooped.
Fred: It may be old, but it's cheap.
Ethel: Well that makes two of you.
This is the last appearance of the Mayer twins who played Little Ricky. They retired from show business.
Song: "Happy Birthday to You" in Italian
This is Kathryn Card's final appearance as Mrs. McGillicuddy on I Love Lucy. She will, however, appear one more time on The Lucy-Desi Comedy Hour.