Continuity mistake: Ethel's full name in this episode is Ethel Mae Potter; however in a earlier episode, Fred calls her Ethel Louise, and in another episode she is called Ethel Roberta.
Revealing mistake: At the Brown Derby, when Lucy bumps into the waiter causing him to trip and spill the tray all over William Holden, we can see that the waiter's hand is taped to the bottom of the tray for the stunt to be done efficiently. (00:15:15)
Continuity mistake: At the start, when the Pontiac convertible turns into the driveway of what should be the Beverly Palms Hotel, the sign with the real name of the hotel can be seen, which reads Beverly Carlton Hotel.
Don Juan and the Starlets - S4-E18
Continuity mistake: After the maid sees Lucy sleeping on the couch and leaves, in the next shot the clock reads 10:00 and Lucy wakes up, but when Lucy checks the bedroom and walks back into the living room, the clock now reads 6:40. (00:16:25)
Don Juan and the Starlets - S4-E18
Visible crew/equipment: After Fred fibs to Lucy about Ricky spending the night, when Fred walks over to the door just as Ethel walks in, we can see the shadow of the boom mic moving at the top, right corner of the screen. (00:18:30)
Hollywood Anniversary - S4-E24
Visible crew/equipment: After Lucy rushes out with the newspaper to tell Ethel about all the movie stars coming to the party, when Lucy returns to the suite and closes the door, we can see the arm of a crew member and a board with "DPI" (Desilu Productions Inc) on it, at the bottom right side of the screen, and a bit of equipment at the top right corner. (00:15:00)
Hollywood Anniversary - S4-E24
Continuity mistake: In season 2, "The Anniversary Present," Lucy has the 19th circled on the wall calendar, which is the date of their wedding anniversary, but in this episode when the license bureau in Greenwich, Connecticut sends Ricky a telegram with their wedding date, it's now on the 7th.
Continuity mistake: When Lucy's locked out on the penthouse balcony, Ethel places the broom handle through the small round finger hole of the scissors, with the large oval finger hole to the right of the round hole and the blades pointing out, then holds the scissors in place as she puts the broom over the balcony rail. When Lucy retrieves them from the broom, the scissors have flipped over. The blades are pointing out and the broom handle is still through the small round finger hole, but now the large oval hole is to the left of the round hole. (Impossible to do on its own. Try it). (00:19:05)
Character mistake: When Lucy and Harpo are doing the mirror routine, Harpo grabs the horn on his belt with his right hand. For Lucy to create a "reflection", she would need to use her left hand but she uses her right hand.
Revealing mistake: At the end of Lucy and Van Johnson's dance, Ricky and everyone else clap as Lucy walks through the curtain to head "backstage', and in the next shot just as Lucy walks through the curtain we catch a glimpse of Desi Arnaz standing there waiting for his cue. Then in a few moments Ricky, Ethel, Fred, and Caroline all rush in excitedly to congratulate Lucy. (00:24:55)
Other mistake: Lucy walks out on the balcony and sees Van Johnson sleeping on a lounge chair by the swimming pool. The photographic backdrop shows automobiles, trees, mountains, the Roosevelt hotel and many other buildings of Hollywood but when Lucy goes to the pool and sits on the lounge chair next to Van Johnson, the background is just a plain painted backdrop with no cars, trees, mountains or buildings. This plain backdrop also appears in the episode with Harpo Marx.
Deliberate mistake: After Fred and Ethel arrive at Richard Widmark's house dressed as mental hospital staff, when Lucy hugs Ricky and holds out the grapefruit for Widmark to sign, the last closeup of the adorable St. Bernard is a flipped shot - note the chair in the hallway which should be to the left of the table, but is now to the right of the table. (00:25:05)
Plot hole: A block of cement that big would be very heavy, far too heavy for Lucy and Ethel to carry, not to mention someone would have noticed them carrying back to their hotel room.
Revealing mistake: Lucy, Fred and Ethel are admiring the celebrity footprints in cement outside Grauman's Chinese Theatre in Hollywood. In several scenes, the shadows cast by Lucy, Fred, Ethel and a passerby make it very obvious that what appears to be the ticket office, entrance and front wall are actually just a painted backdrop.
Visible crew/equipment: When Ricky is with John Wayne in his dressing room at the studio, getting yet another set of footprints on the block of cement, three T-marks are visible on the floor. One of those T-marks can be seen closeup when Wayne is lying on the table for his rubdown. (00:18:10)
Visible crew/equipment: When Ethel walks into her hotel room and tells Lucy and Fred about having to push the motorcycle to three different places, the second camera (or other equipment) keeps moving in and out of shot at the right side of the screen. (00:13:00)
Continuity mistake: The Mertz' check out of the hotel and are in the garage on a motorcycle. Later they are back in their hotel room with Fred napping in a chair with a hurt shoulder.
Suggested correction: Ethel and Fred checked out of room 317, intending to leave. Later, after their motorcycle crashed, Ethel and Fred checked back in and were given room 372 (time codes 00:09:05 and 00:12:15), so Fred (with his hurt shoulder) is napping in the chair in his and Ethel's new room. There's no continuity mistake.
The Great Train Robbery - S5-E5
Revealing mistake: When Ricky and Lucy find their train compartment, while they stand outside their door talking we can see the actor playing the porter peeking out of the next compartment's door waiting for his cue, and in a few moments he opens the door just as Lucy approaches. (00:02:20)
Homecoming - S5-E6
Visible crew/equipment: During the episode a small tape mark is visible on the floor between the coffee table and the couch, and a T-mark can be seen on the floor near the desk, such as when Lucy starts telling her guests about their "fabulous" trip, Ethel stands at the T-mark and a female guest stands at the tape mark. (00:07:05)
Homecoming - S5-E6
Revealing mistake: In the scene in the Ricardo's kitchen, after Fred enters through the rear entrance the door is left open. Through the doorway one can see at a certain point, not just the NYC real estate in the distance but apparently a blown-up photograph of what "appears" to be a man and woman sitting at a small table in a cafe. However, in a subsequent episode of the same view through the rear door it appears that the exact same background photo shot may actually be, not a man and woman but features on the outside of a building, such as one or more windows.
