The robber known as Madame "X" is on the loose, and everybody is scared where she'll strike next. Due to wacky circumstances, Ethel thinks Lucy is Madame "X," and Lucy thinks Ethel is Madame "X." They each try to catch the other.
- The original script for this episode had Madame "X" get away at the end, taking both Fred's new birthday tweed suit and Fred's old suit Ricky took to the tailor's along with her.
- The Mertzes try to get Lucy's fingerprints on the silver cigarette case Ricky got from his band. Engraved on it was: "Merry Christmas to the boss from the boys, 1952."
- Although the episode is not titled as such, Fred's birthday is going to be celebrated very soon.
- Lucy and Ricky want to buy Fred a tweed suit for his birthday.
- At the beginning of the episode, Lucy and Ricky are surprised to learn that Fred's birthday is coming up soon. This is odd, considering the many years the Ricardos and Mertzes have been friends.
- The night this episode aired was the night of the surprise anniversary party Desi had for Lucy at the Mocambo, the same party that will inspire episode #121's plot next season. During the party, a TV was brought into the Mocambo so the guests could watch this new episode.
- The police figured out Madame "X" was a woman robber when they saw her hitch up her girdle. Everyone thought she was a man at first because she dressed in men's clothes.
- The Ricardos' good silver belongs to Ricky's mother.
- In this episode we see a second window with a fire escape in the bedroom along the usually unseen fourth wall
- Lucy: Well, get the police, get the police! (to cop) Oh, YOU'RE the police!
- Fred: I was not hidin'! I was lookin' for somethin' to hit [the burglar] with!
Ethel: Under the bed?
- Lucy: Come on, Fred. Don't be bashful. How old are you?
Fred: Well, I'll make a deal- I'll tell how old I am if you'll tell how old YOU are.
Lucy: That was a big robbery last night...
- Fred: (singing to tune of "Happy Birthday") New door locks for Fred, new door locks for Fred! New door locks for Fred...
- Ricky: Well, honey, they have to know is measurements.
Lucy: They do?
Ricky: They do unless you wanna give him a tweed nightshirt.
- Fred: So, she took one of my suits. Ethel, there are a hundred reasons why Lucy could take one of my suits.
Ethel: Name a few.
Fred: Well, it could have been... Well, she might have had... So, Lucy's Madame "X"!
- Ethel: If she doesn't put on your suit and go out and come back later with a bag full of loot, then she isn't Madame "X."
Fred: That won't prove anything. Even a crook has a night off!
- Lucy: (to Ethel) On a diet? Why, you don't have to reduce. If anything, I'd say you were UNDERweight.
Fred: Have you been to an oculist lately?
- Lucy: (to Madame "X," thinking it's Ethel) If it's money you need, I'll pay you what I owe you!
- Fred: Which way did she go?
Ethel: She went that way!
Fred: (pointing) This way?
Fred: You sure?
(Fred runs off in opposite direction Madame "X" went)