The new girl at school, Amy, is wearing a dress made of the same fabric as the two blue, white flowered, "Sunday Best" dresses Ma made for Laura and Mary in the first season. Could be one of the actual dresses, although this is a few years later, and the dress looks quite new.
The black cat that belongs to Nancy will also appear as Laura's cat on the episode of Days of sunshine and days of Shadow on both episodes of part 1 and 2.