Factual error: About 1/3 through the show, Greg has to talk to Marcia and asks Peter to leave. On the way out Peter stops to start recording on the tape recorder. He only pushes the play button. He would have had to push the red record and play button to record their conversation.
Visible crew/equipment: As Mike gets up from the table after lecturing the girls, the boom mike's shadow becomes visible on his back. (00:15:00)
You Can't Win 'Em All - S4-E22
Continuity mistake: The dress in Cindy's arms turns around from one shot to the next; first the back is facing outward, then the front is. (00:14:15)
The Power of the Press - S3-E19
Continuity mistake: The book Peter's classmate is holding rotates between shots. (00:10:00)
Audio problem: Many times throughout this episode, the actors' voices echo, especially when Mike yells out to Peter (and vice versa) from different rooms.
The Great Earring Caper - S4-E20
Visible crew/equipment: The stage lights are reflected in Peter's magnifying glass. (00:04:00)
The Big Bet - S3-E18
Revealing mistake: When Bobby closes the sliding door behind him, the curtains swing outward and through where glass should be, revealing it to be an empty frame. (00:01:15)
Continuity mistake: When Greg runs into the girls' bedroom to rescue Bobby from the window ledge, there's a black stuffed animal sitting in the middle of the bed nearest the door. After Greg pulls Bobby into the room, the stuffed animal is at the head of the bed. (00:03:45)
Continuity mistake: The football diagram that Greg draws on the chalkboard changes from shot to shot. (00:07:00)
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)
Goodbye, Alice, Hello - S4-E10
Continuity mistake: Greg is wearing dark dress shoes when he comes in to the yard playing football with Peter. When they enter the kitchen, Greg is wearing white sneakers, and when Greg enters the living room, he is wearing the dark dress shoes again. (00:01:15)
Snow White and the Seven Bradys - S5-E3
Continuity mistake: During the play, Mike's "Prince Charming" hat disappears and then reappears when he leans over to kiss Carol. (00:22:15)
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.