In the season two episode, "The Gift", Mary and Laura are fishing when their Pa comes down to fish with them. Mary is about to tell Pa about the medicine they bought with the Sunday school money, when she gets nervous and tells Pa that she will pick berries. In the beginning of this scene, Mary is wearing a blue pinafore over her pink dress, but when Laura and Mary are walking up the hill, we see that the pinafore is gone; Mary is just wearing the pink dress!