By the way, while watching this episode I noticed a certain "ghostly" apparition after Peter runs into his double in the school hallway. As Arthur rises into frame, you can see an old man's profile rising with him, just peeking past the split-screen line. Apparently, this was a stand-in used to match the actor's movements between the two exposures. The fact that it's an old man's profile adds an eerie quality to it, and I bet if VHS had been available back in 1974 that more people would have noticed and possibly concocted stories about the ghostly image (like what happened with the unintended appearance of the cardboard stand-in from Three Men and a Baby). Here are a couple of stills of the profile from the video. (The extra profile does not appear on the DVD version of the episode.)
Don't miss the other Brady Bunch episodes: "To Move or Not To Move", "The Slumber Caper," "Fright Night," and "Out of This World."