The Hustler - S5-E21
Audio problem: Bobby is lining up a pool shot. There's a cut to Cindy, and as she says her line, the sound of pool balls being hit is heard. But when the pool table is shown again in the next shot, none of the balls have moved. Also the pool table moves from outside to inside. Lots of mistakes with the balls on the table throughout the game. (00:08:25)
The Hustler - S5-E21
Audio problem: There's an ominous mic echo when Bobby is talking with Mike's boss at the pool table, indicating this was filmed on a sound stage.
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.