The Winner - S2-E21
Continuity mistake: When Mike and Carroll drive Bobby to the TV show for the ice cream eating contest they leave in the blue convertible. They return home in the brown station wagon.
Continuity mistake: When Cindy goes downstairs to ask "isn't anyone coming up to say goodnight?" or something similar, when Alice is talking to Mike and Carol about Sam not coming over, Cindy is wearing her pyjamas. She then gets in trouble and goes straight back up to her room and she is suddenly dressed in jeans and a top - her hair has different hair ties in it too.
The Not-So-Ugly Duckling - S2-E9
Continuity mistake: When Jan comes home and tells her parents that Clark didn't notice her at school, she's wearing a white blouse with a floral design and a red ribbon in her hair, but when she gets to her bedroom and accuses Marcia, she's wearing a striped blouse and a light green hair ribbon. Then when Jan talks to Greg she's wearing a green tee shirt and a dark green ribbon, but when she asks permission to go to the store she's back in the striped blouse and light green ribbon.
Confessions, Confessions - S2-E12
Continuity mistake: When the vase gets broken, it's easy to see that one large piece flies off the chest of drawers onto the floor. And when the boys look down at the broken vase from upstairs, three pieces are on top of the chest of drawers. But Greg - seen later trying to fix it - says something to the effect of "Good thing it only broke into three pieces." So what about the piece that flew off onto the floor? (00:02:00)
The Un-Underground Movie - S2-E4
Continuity mistake: During the filming of Greg's movie, Mike is in the stockade when Peter dumps the box of "snow". When the family sits to watch the film, Mike is released from the stockade by Carol before the snow is dumped. (00:17:45 - 00:20:10)
Continuity mistake: Cindy's notebooks keep changing in number and color during Peter's confrontation with Buddy. (00:21:30)
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)
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 number and position of the darts on the dartboard changes between shots. (00:06:45)
Continuity mistake: Through the course of the episode, Greg has a spot in his eyebrow over his right eye that switches from shaven to unshaven.
Continuity mistake: The horse figurine and telephone on the table next to Greg are not in the same positions from shot to shot. (00:07:15)
Confessions, Confessions - S2-E12
Continuity mistake: The vase broken by the ball is obviously not the same one dropped by Carol at the end of the episode. The first one was thicker and darker. (00:02:15 - 00:24:05)
The Winner - S2-E21
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)
Continuity mistake: The home number Mike dials in the men's bathroom to check on the kids, is very different than the home number Carol dials in the ladies restroom. (00:18:30 - 00:18:56)
Continuity mistake: When Bobby attempts to climb the treehouse for the second time, he climbs to the very top and looks up in fright. From his POV we see he has two more wooden bars to climb, despite being at the top a split second ago.
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.