Behold, a Distant Star - S2-E10
Stupidity: When Johnny finds out his father is alive and wanted for murder, he is livid with his sister for telling him neither fact. When Sue decides to tell him the whole story, she asks Reed to pull a photo album from the drawer next to him, which contains a newspaper clipping detailing that their father was wanted for murder. If Sue didn't want Johnny to know about that, she shouldn't have placed the clipping in a photo album, and then kept the photo album in a communal area where Johnny could have easily discovered it at any time. (00:06:19 - 00:07:34)
The Promise - S6-E13
Stupidity: Markham lets Ava call her uncle's phone, and she doesn't let on that Boyd answers instead. He later says "I don't trust anyone", but he didn't demand she put the call on speaker for transparency, he's quite happy (at the time) to just hear one side of the call.
Stupidity: Recurring issue when Ahsoka is fighting with dual sabers - there are often times in a duel when one saber is clashing with the other person, but she still has a hand free with her shoto that she could use to stab/slash and win the fight easily. Would make for shorter battles of course.
Stupidity: This highly prepared organisation knows Dracula is coming, but comes armed with guns they're not prepared to use, and allow him to grab a weapon and shoot one of them. Then they give him a tablet but assign the most basic of passwords to the Wi-Fi, rather than disabling it entirely, or even just giving him a Kindle, given the only point of it was access to books. Plot-serving idiocy.
Free Family Portrait Studio - S8-E24
Stupidity: Dwight is seen walking out of the bathroom with the diaper in the direction of the main part of the office in which Angela sits. If he was to try to stay hidden (which was obviously the whole point), he would have gone through the exit of the annex, waited until she was distracted/or hide it for later and Angela never would have seen. This was done because the plot required for Angela to notice but Dwight could have easily kept it hidden. (00:10:40)
The Succubus (a.k.a. Chef's Mama) - S3-E3
Stupidity: When Kenny and Cartman are sitting on the bench, Cartman can't start the tape as he has fallen asleep. Kenny then tries to wake him up, but wouldn't it have made far more sense for him to just start it himself, as he is sitting right next to it? Cartman's job was to push the play button. It was not like he had to rewind, fast forward or even eject the tape, so all Kenny had to do was just simply push the play button and tape would have started to play.
Stupidity: Ahsoka is fighting against the spear-wielding woman. She keeps blocking the spear using both her sabers. It would be very straightforward to block the spear with just one lightsaber (as she proves she can do just as well after she loses the smaller one) and use the second one to, for example, cut off the woman's hands.
Suggested correction: This is opinion, not stupidity.
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?
Stupidity: When the new principal is addressing the student body, Avalanche tries to impress Kitty by causing a couple of small earthquakes, one of which causes the scoreboard to crash to the floor below. The principal laughs off the incident and continues to address everyone instead of either evacuating the area or having everyone take cover.
Lucifer, Stay. Good Devil. - S1-E2
Stupidity: It takes an awful lot of pointless visits and oblique thinking to simply investigate the known (and apparently only) collaborator and protege of the suspect, who also was on the crime scene. You'd think interrogating the business associate would be standard procedure.
The One With All The Rugby - S4-E15
Stupidity: Emily tries to help Ross inflict pain on the other rugby players and tells him about one player who doesn't wear a cup. No one who knows rugby would ever wear a cup, it is more hazardous than helpful to wear a cup in rugby as it involves a lot a grinding, and a simple slip or movement could cause serious damages to the male genitals. Especially if these guys are British and well versed in rugby which they are.
The Clean Room Infiltration - S8-E11
Stupidity: On the way home from the university after wiping their names from the sign in sheet, Leonard, Howard, and Raj are all singing Jingle Bells. Leonard is driving and has his eyes closed all the way through singing the song, this makes no sense at all giving he should be looking where he's driving.
Will the Real Martian Please Stand Up - S2-E28
Stupidity: The whole plot is based upon 6 people not being able to spot the seventh (odd man out). We can eliminate the couples, the driver remembers the pretty blond getting on the bus and the crazy old guy would stick in anybodies memory, so it leaves only the sour old guy in the coat and hat as the martian.Also all the troopers has to do was ask for IDs which they do but quit after they ask the crazy old guy for his.
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)
God Complex - S5-E23
Stupidity: Maggie and OA are searching the building. As they walk up the stairs, Maggie is using the Harries technique, but she has both her handheld flashlight and the gun's flashlight on at the same time. This defeats the purpose of the technique. Additionally, it's daytime, so the building is lit up from natural light sources, but they still have their flashlights on. (00:13:36)
A Knight of the Seven Kingdoms - S8-E2
Stupidity: It is decided that those who cannot fight will hide in the crypt from the army of the dead, and Jon Snow suggests during the war council to put Bran in the crypt as well, "where it's safest." Jon knows full well that the Night King can resurrect the dead and add them to his army. Not only should he not suggest to hide Bran there, he should be telling everyone not to go anywhere near the crypt.
Stupidity: When Franklin and Tara are hooking up at the motel, it appears that sunlight is shining through the windows. Franklin is unaffected.
Halloween 2: The Ghost of Hetty's Past - S2-E5
Stupidity: If Sam was so worried about conserving oxygen, she should have blown out the candles in The Vault.