When Joel is at the garment factory, he opens a door to the stairwell where he finds Manny standing on the landing, smoking. Joel says he shouldn't be smoking there, asking "Remember the Triangle Shirtwaist Fire?" to which Manny replies "Like it was yesterday." The Triangle Shirtwaist Factory fire occurred March 25, 1911, and is one of the most infamous incidents in American industrial history, as 145 workers perished in Manhattan. The tragedy brought attention to sweatshop conditions and led to better laws and regulations for worker safety. The fire was thought to be caused by a lit cigarette tossed into a bin of fabric scraps.
When Rose goes to the Rodin Museum in Paris with her art class, on a sidewalk across the way is a small line of little girls with a nun at the front and rear of the line. This is no doubt a reference to Ludwig Bemelmans' famous children's book, Madeline, which told of "...twelve little girls in two straight lines..." as they moved through Paris. [The piano bar at the Carlyle Hotel on East 76th Street in New York is named after Bemelman and its walls are covered with murals from his drawing including some from Madeline.]
The television show that Susie and Ethan are watching is Andy Griffith, Steve Lawrence & Eydie Gorme, The McGuire Sisters (1958), which was released on 7 September 1958. This is the only time where Steve Allen, Andy Griffith and The McGuire Sisters are billed together on TV.
When Joel leaves a message for Midge to meet him at 15 West 40th where he is viewing an apartment he thinks she will like. They get into an argument and Midge tells him he should live in Turtle Bay.
Turtle Bay is a neighborhood in Manhattan roughly from 43rd Street to 53rd Street, from Lexington Avenue to the East River.