Stupidity: When the Duel Ghouls are present, they are always treated as a genuine threat and an obstacle for the main characters. However, they are never shown to be violent or aggressive, or force anyone into a duel, and the only way they can take someone down is cause them to run out energy through the bio-band, which is only possible by duelling them. So, all the characters had to do was simply ignore their duel request or push them out of the way.
Breaking of the Sacred Seal - S3-E23
Stupidity: Echo has several bombs planted across the excavation site, which she threatens to activate with a detonator that she is holding if Pegasus or his aides get any closer. When Pegasus says "On my mark" to his aides, Echo says "Don't come any closer" and the aides then charge at her. There was ample time for her to activate the detonator when the aides were running up to her, but she doesn't, which leads to her plan getting thwarted. (00:14:04)
Stupidity: Jaden places a wet cloth on Blair's forehead. However, he places the cloth on top of Blair's fringe, instead of brushing it away, which would make it harder for the water to touch her skin. (00:03:02)
Stupidity: Right before the duel with Miss Fontaine, Jaden tells Jesse to sneak around and give the first aid to Blair. Rather than do exactly that, Jesse decides to stand behind Jaden and watch him duel for a few minutes, instead of going over to help her. He even repositions himself to be on Jaden's right, which would make it harder to get to Blair, even though his original position (on Jaden's left), would've made it easier for him to sneak around to her. (00:09:03)
Win Mr. Stein's Duel: Part 1 - S3-E9
Stupidity: Adrian has a conversation with the other main characters whilst he is lying in bed, before they leave. Once they leave, he is revealed to have been wearing gear, which he hid from the other characters by covering his whole body with his duvet. There was no real reason he had to do this; he could've just worn normal clothes during the conversation and changed into his gear after they left. (00:05:39)
Hanging with Axel: Part 2 - S3-E5
Stupidity: Hassleberry and Jesse sneak around Axel to free Syrus from the tree whilst Axel is distracted with the duel. They are trying to be discreet whilst Axel is distracted, but Hassleberry shouts "Hey, Sarge. Open up a can of Neos on this guy" to Jaden, even though Axel would definitely hear this. (00:06:38)
Hanging with Axel: Part 2 - S3-E5
Stupidity: After Jaden summons Neos and Flare Scarab, he has Neos attack Axel directly. Axel uses the effect of his Firewall card to block the attack by removing a Pyro-type monster from his graveyard. After the attack is blocked, Jaden attacks directly with Flare Scarab, causing Axel to lose 1700 points because he couldn't block the attack. But if Jaden had attacked with Flare Scarab first and Neos second, Axel would have lost 2500 points from Neos' attack, instead of 1700 points from Scarab's attack. (00:08:30)
