Maggie is depicted as being an adult woman, older than Emily and Lavinia. In reality, Maggie was over a decade younger than Emily and would have been in her early teens at the time of the series. Maggie did not begin working for the Dickinsons until the 1860s.
Many of the buildings in the fictional version of Amherst are noticeably worn and weather beaten. This is because they are historical houses which are very old. But in Emily Dickinson's time, most of the buildings in town were fairly new. The Dickinson house was only about forty years old. They would mostly look in good repair without the wear and tear of centuries of use.
In several scenes throughout the series Emily Dickinson is shown to have shaved armpits, something quite unrealistic for a woman living in the 1800s.
Though scholars have argued that Emily Dickinson had a romantic relationship with her close friend Susan Huntington Gilbert, that lesbian relationship has never been confirmed. Therefore it's a purely fictional character choice in the series.