The scene where "Nellie" Alison Arngrim was knocked off Bunny by the tree branch was filmed while Allison was sitting down. A piece of Plexiglas was put in front of her face and the tree branch was pulled back in front of the Plexiglas. She was directed to scream and when the tree limb hit the Plexiglas, she was to fall over, making it look like she was knocked off Bunny by the tree limb.
Nellie Oleson Alison Arngrim had a skateboard accident before this episode was filmed. Her arm was broken and she did have an abrasion on her head in real life. The make-up department made her abrasion look new, as it was healing, and her cast was wrapped to make it look like a cast one might get in the late 1800s. That is why her cast is so big.
Actress Alison Arngrim (Nellie Oleson) broke her arm in real life just before filming this episode, requiring a revision of the script.
Bunny is referred to as "she/her" in this episode but as him in the "Christmas at Plum Creek" episode.