During the scene where the students riot in Bart's classroom, Ralph Wiggum is shown eating paste. Ralph has repeatedly been shown to be in Lisa's class.
When the school uniforms start changing colors from gray and white to rainbow colors, Lisa points out the colors and says "red" amongst them, however, there is no red to be seen on any of them. They only have: green, blue, purple, orange and pink.
Skinner makes Bart wear a couch cushion cover home after he is caught with the Mad magazine slogan. However, Bart did have a sweater he could have worn instead.