In Season 3, episode 70 (Cindy Brady, Lady), At nightfall, Marcia and Jan run to answer the phone, and then call Cindy to the phone that its her secret admirer, Mike is standing up to the right, then the shot slightly pans to the left as Cindy runs to the phone. In the next shot, Mike is sitting down comfortably next to Carol. Its unlikely Mike could of sat down in those few seconds from where he was standing.