Before Ralph visits Lisa, she's sitting cross-legged and barefoot, but when Ralph comes in, Lisa is sitting on the edge of her bed and wearing her aqua-green slippers. And then after he leaves and she drops the book on the floor, Lisa is barefoot again.
Two kids in the middle of the class do not have a test. However they are shown writing on their desk.
Otto's headphones change from orange to completely blue after he takes the Atkins mask off and before he stated acting is tough.