Backlash of the Hunter - S1-E1
Stupidity: Rockford knows almost nothing about the guy who is tailing him except that he noticed him while he was grabbing a bite with his client. Regardless of that, he sends the same client to seduce him, just assuming that he won't be able to recognize her. And it works. Is Lindsay Wagner this hard to forget, that this guy just an hour or two later isn't able to tell it's the same woman his target was meeting?
Stupidity: Eve, the assassin trying to kill the Senator, tells Cole to move or she'll shoot through him, rather than just shooting him. She already killed an agent by shooting him in the back and had plenty of time to just shoot Cole, so there's no reason for her to avoid killing him.
Stupidity: During a raid of a Latin stash house, Hailey and Kim find two girls with a pistol. In Spanish, they say no bullets. Kim interprets what the girls say and Hailey replies, l didn't know you spoke Spanish. Makes no sense that a partner on an elite police unit in Chicago would not know a member of the team speaks Spanish. (00:14:58)
Episode #1.2 - S1-E2
Stupidity: The part when the Colonel and the governess pose as journalists does not make sense. It's far-fetched enough that after a lengthy interview about the culprit's fortune the topic of his family never came up, considering it was one of the main goals and an ideal question to lead with, but considering that "mr. Todo" does not want a picture taken and has a tight security, there's no way that a photographer carrying a large 1930 camera would have been allowed into the interview room to begin with.
Stupidity: After Bernie discovers a treatment for the infection, radiotherapy, everything goes back to normal. Except the contagion is airborne (which is why they were going to flush the entire ship's atmosphere), so they're just going to re-infect themselves in a few hours. And there's only one room on the ship that can be exposed to stellar radiation, so there's no way to clean the atmosphere either.
Welcome to Hotel del Luna - S1-E1
Stupidity: The Mayor realises that Man-wol has approached him and taken out her rifle to shoot him with. Yet during the entire time she takes to aim the rifle at him and fire, the Mayor makes no attempt to flee the stage for his own protection. (00:38:15)
Stupidity: Harold isn't sure whether to trust the flash drive Claire gives him, worrying connecting it to his laptop will send Samaritan all his personal connections. Somehow it doesn't occur to him to just use a completely disconnected / airgapped laptop, in a Faraday cage or similar like the one he kept Root in. If the flash drive had malicious code on it, nothing could be transmitted anyway.
The Power of the Doctor - S13-E9
Stupidity: After the crew of the space train have taken out the Cybermen, the Cybermen begin regenerating, which one of the crew points out. This guy seems to be aware of how regeneration works, but doesn't shoot at them again. In the series, it has been shown that shooting someone during a regeneration cycle will kill them instantly, but this idea is never considered.
The Pin-Up - S7-E17
Stupidity: After Erin leaves with the military captain to Camp Lee, John and Maryellen turn around to see John Curtiss nowhere around on the porch where Maryellen left him. So John goes off to look for him, while Maryellen goes in to check The House. John Curtiss is a one-year-old baby who couldn't open a door.
Girl Trouble / School Dance - S3-E18
Stupidity: Girl Trouble: In class, Helga pranks Arnold by putting glue on his chair. Arnold sits in the chair and gets glue on him. Why would anyone not look at the seat before sitting? (00:03:14)
Suggested correction: Plenty of people don't look before sitting down. I once had someone put a pin on my seat in school and I didn't see it.
I can understand one not catching a small pin on their seat (or clear coloured glue). In fact, that is a pretty common prank. The thing is, Helga put a whole bunch of white glue on Arnold's chair, something so blatantly visible, unlike the other stuff I mentioned. It's just strange to me that Arnold wouldn't see something like that before sitting down in his chair. This also goes for my other entry that you added the same correction for.
Who, What, Where, Wendigo? - S2-E10
Stupidity: Dwight, Audrey, and Nathan all know Dwight's trouble is that all bullets are attracted to him, so why is he with them when they go looking for the killer, knowing every one is using a gun?
Camp Redwood - S9-E1
Stupidity: Brooke leaves her apartment window open as she sleeps, even after telling her friends that serial killers (like The Night Stalker) strike during the summer when everybody leaves their windows open.
Stupidity: Despite being a high-profile fugitive who was a local celebrity in his previous life, Saul does very little to alter his physical appearance, settling on just a mustache and glasses. Growing a beard, wearing a hairpiece, and altering his speaking voice around others would have gone a long way in preventing him from being made.
The Perks of Not Being a Wallflower - S1-E3
Stupidity: Superman finally smashes the weirdly strong bad guy through a wall, then goes to Lois, says "he's gone", and whisks Sarah to hospital. But he has no idea if the bad guy is "gone" or not - they've just had an epic fight, he has some sort of super strength / resilience, and for all Superman knows he'll come around in 10 seconds and finish the job of murdering Lois.
Suggested correction: Superman knows the 'strong bad guy' is close to his own strength. After fighting him, he knows what effect the crash through the wall would have had on him, if he was knocked out, and how long he would be out for. So he knew there was little risk of the guy coming around in 10 seconds. Alternatively, he X-ray scanned the area and saw the guy was no longer there.
Stupidity: Dr. Greg seems to catch some of the more obvious quirks of inmates attempting to take a large vial or bottle from the cabinet. Yet he doesn't seem to notice when Lizzie grabs a bottle of pills and pockets them from the rolling cart in front of him. (00:20:15 - 00:20:45)
Stupidity: The inspector knows that his house has been bugged; he does not know how many bugs and cameras are there, he just knows there are some. He does find a bunch of them with great ease when he gets back home - making you wonder how could he have ignored them to begin with, since all it takes is for him to raise his eyes, they are fairly big black cameras who do not camouflage at all for the most part. He then proceeds to make a phone call to the big baddie from his landline. Nobody in their right mind would do such a thing. Heck, you wouldn't want to use your home phone for such a call even if you didn't know that someone just put bugs all over your house.
Worlds Apart - S1-E2
Stupidity: The bad guy kills the deputy in the swamp, then later sees a little girl who witnesses the killing run away. He then searches the boat for a weapon and runs off after her after he finds a machete, without even considering the officer's gun still in its holster. Abby proceeds to make the exact same mistake later when she finds the dead officer (meaning there's danger nearby) and hears the girl screaming and runs in the direction of the screaming without taking the gun to protect herself.