Continuity mistake: When Greg and Marcia are taping the fake message for Peter, Greg says, "Bang, he buckles down and brings home an A." But when Peter listens to the message a minute later (16:15), Greg's statement is now "Bang, he brings home an A." (00:14:50)
Continuity mistake: The shadow (supposedly of the window frame) on the headboard of Jan's bed changes from one shot to the next. (00:24:35)
Continuity mistake: When Marcia takes her last turn placing a card at the top of the tall house of cards, in the shots facing her she's stressed about accidentally collapsing the cards so she holds back her charm bracelet with her left hand, but in the first shot facing the three boys Marcia's left arm is down at her side and the charm bracelet is dangling at her wrist, right beside the cards. (00:21:00)
Everyone Can't Be George Washington - S4-E12
Continuity mistake: When Jan's in the backyard checking on the cloud and moon set decorations being painted by Marcia and Cindy, there's less "dark and gloomy" paint actually painted on the cloud after Cindy stands up with the smiley moon. (00:06:20)
Continuity mistake: In the photo of the football reception, the enlarged photo is not from the original. The receiver's legs are in a different position. (00:22:35 - 00:23:20)
The Impractical Joker - S2-E13
Continuity mistake: While Myron is on the closet shelf with Carol's shoes, the camel colored shoes repeatedly change between having camel colored heels to dark brown heels. (00:11:35)
Continuity mistake: In the courtroom, as Carol is giving the judge her side of the story, she's looking in the direction of Mr. Duggan the whole time while saying "otherwise he wouldn't have hit me." Then the camera changes angles and instantly Carol is turning from facing the judge back towards Mr. Duggan.
Continuity mistake: During the filming scene near the end of the episode, Bobby's hat transitions from being in his hands to back on his head, untouched.
Is There a Doctor in the House? - S1-E13
Continuity mistake: When Carol and Mike are bringing stacked lunch trays upstairs to the kids, the milk glasses on the middle and bottom trays that Carol's holding switch to the opposite sides twice, in the wideshots and closeup. Then when Carol picks up the girls' stacked trays, the glass of OJ is on the bottom tray (after Peter's reaction to broccoli, it looks as if the OJ glass is gone), then as Carol walks into their room the OJ is now on the middle tray.
Continuity mistake: While the kids are practising the potato sack race as Jan watches from the sidelines, when Marcia steps into her sack and hops away there's a large color image on the front of the sack, but when she reaches Peter, then turns and heads back the image has vanished - it's not on either side, then it reappears when she's back with Bobby. Additionally, when Cindy hops in the sack that Greg was in, the sack is ripped at the bottom and Cindy's feet are on the grass, but when Cindy reaches Peter the bottom of her sack is perfectly intact.
Continuity mistake: At the start of the episode there's a wide shot of the house exterior as the Brady's station wagon is pulling into their driveway, and the wagon has wooden side paneling, but in the next closeup the paneling is gone. Plus the fact that the rear-end damage doesn't exist in the first wide shot, which is the point of this episode.
Lost Locket, Found Locket - S1-E25
Continuity mistake: Jan puts her bathrobe on, flipping all of her hair behind her back. But in the next shot, some of her hair is over her left shoulder. (00:20:30)
Continuity mistake: In a close-up of Mike's hands as he undoes his seat belt, he isn't wearing his wedding ring but he is in subsequent shots. (00:04:15)
Continuity mistake: The tents are small from the outside, but much larger when seen from the inside. (00:18:25)
Continuity mistake: Near the beginning, Greg is painting the shutter green, he gets a phone call and goes inside. The paint bucket falls on Bobby because the ladder falls. Greg sticks his head out the window and asks who took his ladder. The shutter now has no paint on it.
Continuity mistake: When Cindy gets out of bed to write a letter to Joe Namath, they show the wall next to Jan's bed and there is no window. In a previous episode Jan lost the locket out that window that Alice sent her.
Confessions, Confessions - S2-E12
Continuity mistake: When the boys are playing ball in the bedroom, Greg has on a pair of dark jeans. When they go downstairs to see the broken vase, he is wearing a normal pair of blue jeans. (00:01:30 - 00:02:30)
Continuity mistake: The bottles of pop on the kitchen table keep changing position from shot to shot. (00:22:55)
Continuity mistake: The number and position of the darts on the dartboard changes between shots. (00:06:45)
Continuity mistake: The amount of garbage in the abandoned house - especially in front of the fireplace - increases from one shot to the next. (00:16:20)
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.