Stupidity: After Cory and Shawn fish Mr. Feeny's watch from the septic tank, he suggests they jump into the lake to clean off. Cory protests, reasoning that it's only 20° outside, to which Feeny dismissively tells them to take a sweater. They then reluctantly abide. Someone of Feeny's education should know better than to allow them to jump into a freezing cold lake. They could both get hypothermia, and they're all currently isolated in the Pocono Mountains with no nearby medical facilities.
Stupidity: When Eric, dressed in drag, tearfully sits down next to Topanga, she asks him if they know each other because she doesn't realise it is him. Topanga's known Eric practically her entire life, and she is one of the smarter characters on the show. Given that Mr. Feeny instantly recognized that Eric and Jack were dressed up as women, Topanga should have recognized it immediately as well. (00:10:40)
Suggested correction: This is a comedy show and this scene is played for laughs. A character not recognizing another character in drag when it is obvious to the audience has been a joke for centuries. Also, on a realistic level, recognizing faces has nothing to do with intelligence.
There's a difference between not recognizing someone you might barely know and being fooled by an obvious disguise worn by someone you've known for 20 years. I fully acknowledge that this scene is played for laughs and that this is a common trope used in movies and television, but the fact that the show went out of its way to show that Mr. Feeny instantly saw through their disguises demonstrates that show itself acknowledged how ridiculous his disguise was, and it was foolish on Topanga's part for not seeing through it.
Truth and Consequences - S3-E7
Stupidity: This episode shows the school's faculty time-clock to be in a common area of the school. Placing a time-clock in such an area would be extremely foolish, as any disgruntled or prankster student could easily mess with a faculty member's timecard. Not to mention the episode shows Janitor Bud bribing a student to clock him out long after he has left for the day.
