Continuity mistake: During the recording of "Time To Change", Jan's hands are always together when she's shown. But in the shots showing just the boys, look at the right side of the screen and you can see fingers (which have to be Jan's since she's standing beside Peter) moving as if they're drumming on something.
Audio problem: Bobby is lining up a pool shot. There's a cut to Cindy, and as she says her line, the sound of pool balls being hit is heard. But when the pool table is shown again in the next shot, none of the balls have moved. Also the pool table moves from outside to inside. Lots of mistakes with the balls on the table throughout the game. (00:08:25)
Continuity mistake: Bobby goes on a television show for an ice cream eating contest. The host of the show takes the spoons away from the contestants, then tells the kids to put their hands behind their backs. Before they do so a close-up shot of Bobby shows him holding the spoon. (00:19:45)
Plot hole: Greg Brady is suppose to be under 21 so he can't legally sign any type of contract, also at the end he rejects his new persona and tears up the contract. Tearing up a contract doesn't nullify it.
Audio problem: When Carol calls and Mike answers the phone, (after Cindy runs and then the entire salad (bowl) falls to the floor) you can hear Marcia and Jan arguing in the background, but that exact (said) audio is looped if you listen closely - it is an argument from an earlier script that is repeated about 6 times or so during the length of Mike's phone call from Carol.
Continuity mistake: During the goat in the master bedroom scene, the flowers on Carol's side of the bed change during the scene. At first there is a pink flower to the right of a white flower, and then it changes to white flower on right of the pink one. In addition, the whole bouquet looks slightly different in different shots.
Other mistake: In one of the final scenes, Peter ignites his volcano on the patio in front of Marcia and the members of the Boosters Club. As the volcano goes haywire, Marcia and the Boosters are shrieking as the lava/mud covers them head to toe. Somehow Peter, who is much closer to the volcano, is unscathed by the eruption and remains free of any dirt.