Julia Gets Her Head Stuck in a Fence - S4-E8
Stupidity: Once he decided to finally saw into the banister, all Anthony had to do to get Julia's head out was to saw through one of the thin posts on either side of her head. Instead, he saws through an enormous section of the staircase, later causing the governor to accidentally fall through. If he didn't realise that, one of the other designers, all who were looking on, should have. It's a lot to presume they all would have been that careless just for the benefit of a sight gag.
Stupidity: Amazing how people on this show, like The Accused here and in the earlier episode "The Chef", are leaving their doors unlocked or no explanations given as to how the actual killer planted the evidence.
Yomigaere! Eiyuu Densetsu - S1-E1
Stupidity: Despite being in training for 6 years at the temple to compete for a magical armor consecrated to a constellation and meant to harness the power of the Cosmos, Cassios and everyone else but Marin (Shaina towards the end) are mistified about the whole idea when Seiya uses it. What in the world have they all been training for, for 6 years, then? Shaina has to be the worst trainer ever. Cassios even calls it a 'superstition', but his master Shaina channels the power perfectly. It's like a Muggle working at Hogwarts and not believing in magic.