The Disappointment of the Dionne Quintuplets - S1-E4
Factual error: When Midge is moving to her parents' apartment there is a stack of books on the table while her son is watching TV. On top is a Nancy Drew book (the back of the book which is yellow). However publisher didn't introduce the editions with the yellow back covers until the 1960s.
Continuity mistake: When Midge is doing her makeup routine, she doesn't have eye liner, then she does, then she doesn't.
Factual error: When in Harrisburg, Susie mentions the Civil War Museum, but that didn't open until 2001.
Suggested correction: She could be talking about another museum (either real or fictional) with the same name that existed in this time period and had since closed. It's a fairly generic name.
Factual error: Midge talks about a 2 for 1 pantyhose sale but pantyhose weren't introduced until 1959.
Suggested correction: Season 1 starts in mid-1958 and goes into 1959, which would coincide with the introduction of pantyhose. Being that New York City is one of the top fashion centers in the world, pantyhose may have been more readily available there than the rest of the country.
Other mistake: When Midge is doing her skit for the soldiers she is pretending to read articles off a magazine. Yet instead of flipping the magazine, she is swiping as if reading off a smartphone.
Suggested correction: "Swiping" is not specific to smartphones or computer tablets. People often do this to speed through books, magazines, or documents, often by slightly moistening the index fingertip, rather than individually turning pages. Midge is pantomiming this her act, so her action is naturally a bit exaggerated for effect.
Factual error: The word "floaties "was not used to refer to pool toys in the 1950's.
Suggested correction: I was a kid in the 50s, and the term pool "floaties" or "floaters" was used. It wasn't commonly used.
Continuity mistake: When Joel is about to start his show a woman in front holds a cigarette with her right hand. In the immediate next angle she's holding it with her left hand.
Factual error: Taxicabs appearing in various scenes show that they are fitted with side marker lights on the fenders. Those were not used on American cars until 1968.
Factual error: Abe hilariously exercises in a ridiculous suit while listening to Robert Preston's "Chicken Fat" recording. But Preston (who starred in The Music Man) didn't release this until 1962, at the behest of President Kennedy, who was big on physical fitness.
Suggested correction: It's true that this song was not recorded and released until 1962, but Abe is not actually "listening" to it (or any other music) as he is exercising on the lake dock. The song is used as part of the series soundtrack and creates a desired effect and mood for the scene. It is appropriate to the era, and is only background music.
It's Comedy or Cabbage - S3-E5
Continuity mistake: When Midge descends the hotel's grand staircase, the piano player and guests are below. Once down the stairs, Midge finds Abe and Rose sitting in chairs with their luggage, just to the right of the piano, in front of a large pillar, with a round sofa behind. However, when Midge was walking down the stairs, the lobby looks different. The piano is in the same position relative to the stairs, but her parents and the chairs are missing and the round sofa is a different style and the shape of the carpeting in front of the pillar is also different.
Factual error: In the Greenwich Village record shop, the vinyl records are shown with polythene sleeves. At that time, vinyl LP's were always factory sealed in cellophane shrink (unless it was later removed), not poly sleeves.
Continuity mistake: When Midge and Susie go see Michael Kessler, one of the mugs on his desk keeps moving between shots throughout the scene.
The Disappointment of the Dionne Quintuplets - S1-E4
Continuity mistake: After Midge puts Joel's ornamental duck down for the final time before she leaves his new apartment, the position of the duck changes in the following shot.
Continuity mistake: While Midge's dad is questioning her about her new job, Midge starts buttering her toast with some jam. But in the following shot there is no jam on her toast.
Mrs. X at the Gaslight - S1-E6
Continuity mistake: The cookie that Midge trades Noah for a cigarette for keeps moving between shots.
Ethan... Esther... Chaim - S4-E7
Factual error: When Midge and Rose leave the club after the magicians act you can see tactile paving at the crossing. This can't be possible as tactile paving was first developed in Japan by Seiichi Miyake in 1965, so they're 3 years too early.
Midnight at the Concord - S2-E5
Continuity mistake: When Benjamin is driving Midge back from the Catskills to New York City, he briefly is driving on the left-hand side of the two-lane country road (which is not a one-way).
Thank You and Good Night - S1-E8
Deliberate mistake: In a flashback to the Maisels' wedding reception (about 1953) Midge surprises Joel by having hired professional dancers, who are shown performing the well-known "Bottle Dance" (the part where they slide on their knees). This dance routine, which is often performed at Jewish weddings and other social events, was actually choreographed by Jerome Robbins for the musical, "Fiddler on the Roof," which debuted on Broadway in 1964. The dance did not exist at the time of Joel and Midge's wedding, but, as an inside joke, while Midge watches the dancers, she says, "That's really good. They should do something with that."