Factual error: When in Harrisburg Suzy mentions the civil war museum, but that didn't open until 2001.
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.
Factual error: The word "floaties "was not used to refer to pool toys in the 1950's.
Continuity mistake: When Midge is doing her make up routine she doesn't have eye liner then she does then she doesn't.
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: Midge talks about a 2 for 1 pantyhose sale but pantyhose weren't introduced until 1959.
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.
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 down 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.
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."
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.
