As Long As We're Together (1) - S5-E1
Factual error: The start of season 5 took place in 1881 (the year Mary first went to the blind school). In 1881, Grace (born in 1877) would have been around 4 years old by then, but she is shown as a baby in the series.
Albert Quinn Ingalls: Ma, please don't tell me I'm too young to know how I feel.
Caroline: I wasn't going to tell you that, and don't ever raise your voice to me while you live in this house.
The Voice of Tinker Jones - S1-E11
Trivia: Sean Penn is in this episode, albeit with no lines, always wearing the same blue shirt. His father directed this episode.