Stay Out Of The Basement (2) - S1-E13
Stupidity: When the real Dr. Brewer is found in the basement, he has duct tape over his mouth and needs his daughter to remove it for him. His hands are tied around the wrist, but not behind his back, so he could have easily removed the tape from his mouth himself long before he was found.
The Return of Hydro-Man: Part 1 - S5-E7
Stupidity: When Spider-Man is working in the lab, he uses his webbing to barricade the door shut so no-one interrupts him. When Debra Whitman shows up and asks who is in there, he identifies himself as Peter Parker. When he is finished with his work, he leaves out of the window so that by the time the security guards break the door down, he has vanished. Since he used his webbing to keep the door closed, it would be pretty easy for Debra and the security guards to figure out that Peter is Spider-Man since Spider-Man's webbing is at the scene and Peter seemingly vanished into thin air.
Laura Ingalls Wilder (1) - S7-E1
Stupidity: Charles and Caroline are dancing at the church social. Charles makes a comment about Laura getting married. Caroline responds with "I'm just dying to call you Grandpa." Mary's son just died. Charles has already been a grandfather. That comment was beyond insensitive, and just plain stupid as written. She should've said, I can't wait to call you Grandpa again.
Stupidity: Sir Topham Hatt is cross with both Percy and James. But why is James being blamed? He had no idea that Sir Topham Hatt didn't actually say that he had to stay in the shed and wait for him. James shouldn't have been blamed since he had thought Sir Topham Hatt actually said that and Percy should've been the only one blamed.
Stupidity: After eventually arriving at the stadium, why didn't Ash tell anyone that he was late due to getting kidnapped by Team Rocket? He arrived with half of his Pokémon exhausted and subsequently lost his battle. If he informed everyone about his situation, his battle with Ritchie would likely have been postponed until tomorrow, giving him some much-needed time to rest, which would have given him a bigger chance to win.
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: Considering he had a watch on in nearly every other episode, the Professor did not have his watch in this episode where they had a rescue deadline time (11:00) to be picked up along with the two Russians. Even if he forgot to put his watch on, he definitely would have paid attention to what time it was and got everyone to the location well before 11:00 to guarantee the rescue. Instead he relied on Gilligan to come up with the time which failed (an earlier submitted entry explains that part).
Long Night's Journey into Day - S5-E23
Stupidity: Rob tells Jerry "I haven't stopped sneezing long enough to take allergy pills" yet right after he says that, he doesn't sneeze anymore till he gives out his home address. He could have just taken his pills then. Someone behind the camera probably reminded him to continue sneezing. (00:16:52 - 00:18:00)
Suggested correction: He's exaggerating, but a character not taking a pill in this situation doesn't constitute a stupidly mistake (minor plot hole). I've been in situations where I needed to take an allergy or pain pill and didn't, even though I had a chance, because my mind or focus was somewhere else.
Snow White and the Seven Bradys - S5-E3
Stupidity: When the kids all pick the random-shuffled papers to choose which kid will be which dwarf, it NEVER occurred to them that with six kids and seven dwarfs they would be one short. This was only discovered once Peter (the last to pick one) was now up for a turn. How did nobody figure that out before the name-choosing even started?
The Secret of the Unicorn: Part 2 - S1-E4
Stupidity: When the Bird brothers are searching the treasure room for Tintin, one of them claims they have found him, and points. The other brother then shoots at him which was turns out to have just been a mirror reflection. The brothers then proceed to find Tintin and start by going straight forward, completely in a different direction than the mirror. If they wanted to find Tintin, wouldn't the more logical thing to do be simply look in the direction the mirror was pointing at? The whole point of a mirror is to reflect what is in front of it, so Tintin would probably have been standing in that direction anyway. (00:37:25)
I'd Rather Twitch Than Fight - S3-E10
Stupidity: Like most dilemmas on the show, the controversy could have been resolved by witchcraft without Darrin knowing. Why didn't Samantha just twitch a duplicate tweed coat?
A Bad Reflection on You - S1-E38
Stupidity: The decision to risk revealing their identities to Bulk and Skull is one that the Rangers could have easily avoided. Since they tell the bullies to cover their eyes and ears, under the false pretense of a magic trick, they could have simply teleported to the Command Center, or any other secure location, and then morphed, well away from prying eyes.
First Kiss - S1-E2
Stupidity: When Jeff Malone leaves the sandwich shop, he leaves the sandwich on the table. It would have been very easy for them to tell what was on the sandwich without needing to wait for Max to get home to recreate it. (00:02:41)
Stupidity: The 10,000 Volt ghost wears a diver's suit to insulate himself against the electricity, yet he doesn't cover his hands.
It's Only Rock and Roll - S3-E11
Stupidity: When the gangsters show up at the house Pam and Dak Hampton are hiding in, Pam is captured. Dak then attempts to flee by running out the front door. What a dumb move. No surprise that he got captured as well.
Stupidity: The Kramden's door opens out towards the hallway. Yet anytime they need to block the door for protection, they put furniture up against it. That would serve no purpose, even with that cheap slide lock they have. The landlord or criminals could just open the door and push the furniture out of their way.