Greg, Marcia, Peter, Bobby and Cindy are practicing for a potato sack race. In the second round for Bobby and Cindy, when they leave the starting line, Cindy's sneakers are sticking out of the bottom of the sack. When the camera turns to watch them at the finish line, Cindy's shoes aren't visible and the sack is clearly sewn shut.
When the Brady kids are practicing for the Potato Sack Race in the backyard, each time they jump, thumps of a wood floor can be heard and parts of the artificial grass seem to be coming apart.
Jan wears two shirts, one purple and one blue, designed for boys/men. Men's clothing has its buttons on the right, and women's clothing has them on the left. In the Renaissance period, ladies were dressed by their servants, and thus the buttons were on the lady's left so the servants, most of whom were right-handed, could more easily button them. Men had their buttons on the right because they dressed themselves, and that custom has prevailed into the 21st century.