Continuity mistake: When Marcia is cheering in the backyard, her locket tucks itself into her shirt when she finishes.
Audio problem: In the scene where Mike comes home and Carol has ruined his golf club, you hear a door open and close, with a latch/doorknob. She hears it and knows he is home. But he comes in the back door, which was a sliding (glass) door. (00:20:00)
Continuity mistake: When Greg comes home after Jennifer gives him her number, Greg is seen entering the house in the living room. Then a few seconds later he is seen entering the other side of the kitchen.
Continuity mistake: Jennifer writes her phone number on Greg's right hand with the first number starting at his thumb, but when Greg looks at his hand to read the phone number, the phone number was written with the first number near his fingers and the last number written by his thumb. (00:02:50)
Answer: Much trivia has been written about "The Brady Bunch, " including the various interrelationships and dynamics among the members of the cast. For example, much has been written about why Robert Reed's Mike Brady did not appear in a couple of episodes, including the series finale, due to rancorous creative and artistic differences with series creator, Sherwood Schwartz. However, in contrast, I have never run across any reasons given why a particular child did not appear in specific episodes - only that the episodes were missed. This suggests the causes were likely unexceptional, such as illness, injuries, vacations, or real-life family obligations.
Michael Albert
Although those options ARE possible reasons, it just seems a bit ironic that this happened all in Season 2 ONLY and within a short amount of nearly consecutive episodes. Never happened during the other 5 years of the show at all.