Top Secret - S5-E19
Revealing mistake: Bobby and Oliver are building a house of cards on a small platform sitting on the table when all of a sudden the house of cards collapses. The reason: the platform moves by itself. Clearly it was manipulated off-screen somehow. (00:01:20)
Top Secret - S5-E19
Continuity mistake: The amount of talcum powder in Bobby's and Oliver's hair increases from one shot to the next. (00:14:35)
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.