Other mistake: When the frog jumps on the pizza (during Greg and Rachel's date), the gooey cheese mess resembles more superimposed tacky glue than actual melted cheese.
Today, I Am a Freshman - S4-E4
Other mistake: In one of the final scenes, Peter ignites his volcano on the patio in front of Marcia and the members of the Boosters Club. As the volcano goes haywire, Marcia and the Boosters are shrieking as the lava/mud covers them head to toe. Somehow Peter, who is much closer to the volcano, is unscathed by the eruption and remains free of any dirt.
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.