Deliberate mistake: In this episode Lucy is trying to get Ricky to notice that their anniversary is on Monday the 19th by showing him a large calendar with the 19th circled. However, when they are in California and they celebrate their anniversary and Ricky asks for information to be wired to him, the telegram tells him that their anniversary is on the seventh.
Continuity mistake: In this episode, Lucy goes out on the window ledge. In "Lucy Cries Wolf", the window ledge was very different: the walls were made of dark brick instead of concrete blocks, there was no downspout, and the ledge went into the corner and stopped, no continuation on the other wall.
Visible crew/equipment: After driving all day, the Ricardos and Mertzes stop by a run-down diner that serves only stale cheese sandwiches, then end up there again only to spend the night in their one motel room. While they're all in their beds, the vibration of the nearby train causes the Ricardos' bed to shakily slide towards the Mertzes and then back again. The wire attached to the Ricardo's bed is visible, and the leg at the foot of the bed is set in a track attached to the floor, which keeps the bed on course.
Visible crew/equipment: After take one of Ricky's screen test, when the director says to Lucy, "I thought it might add interest to the scene if you could make it go around and around like a lighthouse!", the Ricardo's kitchen cupboards and fridge are visible off stage to the left of the director's head.
Visible crew/equipment: After Lucy and Mr. Beecher sign the lease, just as they all start heading toward the door, the taped T-mark can be seen at the bottom of the screen at the edge of the carpet (presumably for the second camera dolly offscreen at the left). Then as Mrs. Hammond walks out, a bit of overhead set equipment can be seen at the top right side of the screen.
Visible crew/equipment: While Lucy and Ethel are at the charm school, when they're standing in front of Miss Emerson's desk, in the widehots a small tape mark can be seen on the floor in front of Lucy's feet. Then when Lucy and Ethel are in sweatpants two small tape marks can be seen on the floor, and when Ethel walks to the other side of the room to join Lucy, there's another tape mark which Vivian even looks down at to confirm her foot's position.
Deliberate mistake: In episode "Redecorating" Lucy wins new furniture, then in the next episode "Ricky Loses His Voice" the new furniture's delivered to the apartment, and the new couch has two normal and identical seat cushions. Starting in the next episode "Lucy is Enceinte" until the episode "Lucy Wants New Furniture", in some scenes the couch has the identical short cushions, however, in other scenes one of its seat cushions (depending on the episode, it's either left or right) is much higher than the other. For example, in "Lucy Hires a Maid" the higher seat cushion's on left side while Lucy waits for her lunch, then after Ethel urges Lucy to fire the maid the short cushion's on the left. The uneven cushions are usually seen in scenes with either Desi or another male actor, who sit on the side of the couch which has the higher seat cushion. There are even scenes where both of the seat cushions are the higher ones, such as in "Lucy's Last Birthday."
Revealing mistake: When Ricky startles Lucy in the kitchen just as she's getting the salt, she climbs up through the kitchen/living room window, and in the shot from the living room when she and Ricky step down onto the chair, we can see the four long metal brackets which bolt the chair to the floor for safety.
Visible crew/equipment: At the start, after Fred and Ethel walk in, when Lucy and Ethel walk away from the kitchen shutters carrying things, the stage microphone and stand can be seen at the right side of the screen. (Later in the episode, when Lucy and Ricky appear on the quiz show an identical microphone is on stage with them).
Continuity mistake: After Lucy tells Mr. Merriweather that he's invited to the seance, when it cuts to Lucy unfolding the card table legs, note the couch behind her with one normal seat cushion on the left, but in the next wideshot there's an additional shorter cushion under the normal cushion. The small towel also repositions itself neatly on the couch.
Continuity mistake: In Lucy's dream, when Carlota Romero comes to their apartment, Little Ricky is sitting in a highchair with a hat on his head. Although later in the scene, you see his hat fall off, the first close-up shot of Little Ricky shows him without the hat. Then immediately, when you see a wide-shot of the scene, his hat is back on his head again.
Factual error: In the film Lucy and the others make, there is a long sequence of footage played forwards, then "mistakenly" repeated backwards. With the equipment and techniques they were using, this would have required not only making a complete copy of the segment, but also reversing the order of individual frames. Just feeding the film in backwards would have also flipped the image vertically. The result seen would be nearly impossible to produce accidentally.
Revealing mistake: While Lucy is out on the ledge, if you look at the pipe as it runs from above the ledge to below it, the two pieces of pipe don't line up. They are off about the full diameter of the pipe. Also when the pipe pulls out, it's obvious the pipe is on a hinge at the bottom and not really attached to the lower pipe. Later, there is also no stream of water falling from above where the pipe was supposed to be connected as a drain even though it is pouring out.
Continuity mistake: In this episode, the Mertzes buy the Ricardo's old washing machine and say that theirs is old enough to be in the Smithsonian, yet just a few episodes earlier ("Sales Resistance") Fred tells Ethel to come and see her new Handy Dandy washing machine.