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: After Walks on Cloud releases Dr Mike, she runs off and hides in a wild thicket as the Dog Soldiers and One Eye look around the area for her. A pair of buckskin are then seen scoping the area, then walking off as Dr Mike leaves her hiding spot and gets 'surprised' by One Eye, who knocks her out. She should have known better and stayed put until sunrise, as Sully taught her when it came to the Cheyenne war parties.
Girl Trouble / School Dance - S3-E18
Stupidity: Girl Trouble: Helga pulls a nasty prank on Arnold in class by gluing feathers to his bottom. Mr. Simmons sees this, but for whatever reason, does not give Helga detention for it. The next day, Helga spills paint on Arnold, then he throws some on her as revenge. Mr. Simmons sees this and gives Arnold detention even though he was simply fighting back at Helga for pushing him too far. Perhaps Mr. Simmons' brain was on vacation those two days. (00:03:16 - 00:08:42)
Claudia and the Secret Passage - S1-E8
Stupidity: The fact that Kristy found the ring that was missing for 40 years just sitting on a windowsill in the secret passage makes no sense; Dawn and Claudia were just by that window earlier in the episode in broad daylight.
Suggested correction: We don't actually see where Kristy found the ring; it was dark, and the girls were chaotic.
Stupidity: In the flashback, Emily's sister takes ill while playing her flute. In the next scene, the sister is sick in bed and Emily now has the morpher around her neck, but she is in the exact same outfit. If the sister was forced to pass the legacy on due to disease, it should have taken more than just a few minutes or even hours to learn that.
Zorro's Ride Into Terror - S1-E8
Stupidity: When Diego sees that the passage door is opened, he invites Sergeant Garcia to sleep in his bed. However, Diego never tries to close it, and during the rest of the scene, nobody (even Captain Monasterio) seems to see it open.
Firefly, Light My Fire - S1-E1
Stupidity: The button Benita uses to open her trap door also turns on/off the record player and swings the record arm.
Norman Mailer, I'm Pregnant! - S5-E6
Stupidity: Luke arrives at Lorelai's house. He comments that she left her car light on. Lorelai then tells him that she left it on because the porch light is out. He says that the battery is going to die. She tells him that she has it timed out perfectly. She then says that there will be 2 hours to spare and that the car has all day to charge. Cars don't charge unless they are running. Is she really going to run it all day? Why didn't Luke point out the error in her logic? Doing so is staying true to the character. The oversight is glaring.
Stupidity: When Richie and Fonzie swap clothing and walk in for The Duel with the Frenchman (both with faces covered to conceal their plan), the whole audience watching The Duel gasp and are all surprised to learn they switched places. But, before the switch was revealed, Richie (as Fonzie) walked in with a nerdier style walk and Fonzie (as Richie) walked "cooler" and looked much more in shape. Also, the head covering Fonzie wore was sheer and you could still see his face, but everyone was STILL fooled.
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.
The Tale of the Dream Girl - S3-E10
Stupidity: A boy walking through the bowling alley stops and lets Johnny pass, even though Johnny is supposed to be a ghost no one can see.