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)
Stupidity: Chazz returns two cards to his deck and redraws another two cards using Magical Mallet. Alexis appears to recognise the two cards (Armed Dragon LV10 and White Vale) calling them "Two very powerful cards." Chazz then summons Armed Dragon LV10 and equips it with White Vale. Alexis attempts to activate a trap, but is surprised to find out she can't, to which Chazz replies the White Vale protects his Armed Dragon, but if she already recognised the card, then she should be aware of this. (00:17:35 - 00:18:30)
Homecoming Duel: Part 2 - S2-E16
Stupidity: Jaden uses the power of contact fusion to fuse Elemental Hero Neos and Neo-Spacian Flare Scarab to summon Elemental Hero Flare Neos without Polymerization. Aster shouts "That's against the rules", but in the previous episode, he saw Jaden summon Elemental Hero Aqua Neos in the exact same way, so he should be aware of this. Or at the very least, this shouldn't be a surprise to him. (00:15:05)
Stupidity: Wheeler gives Jaden a bunch of bananas and then eats two of them. Once he has finished eating them, he walks away and leaves the remaining bananas on the ground. At this point, Jaden is extremely hungry, having not eaten in days and has no idea how long it will take to get Back to Duel Academy, but he leaves behind the only available food to eat. (00:20:15)
Stupidity: When Sartorius first introduces himself to Chazz, he says, "You have a gift, Mr Princeton", to which Chazz asks "How do you know my name" in complete surprise. Even if Chazz is unaware of Sartorius' powers at this point, the Princeton family are very famous and wealthy, and his duel with Jaden was even broadcast live, so it wouldn't be unreasonable for someone to know who he is. (00:07:20)
Graduation Match: Part 1 - S1-E51
Stupidity: Zane activates the spell card Polymerization and explains that "by sending some select monsters from my hand to the grave, I can summon a Fusion monster", to which Jaden replies "To the grave?" as if he is completely surprised by the fact that the monsters will go to the grave. Jaden is completely familiar with Polymerization and has used it in nearly every duel, so he should be aware that the monsters will be sent to the graveyard when Polymerization is used. (00:07:42)
Tag Team Trial: Part 2 - S1-E11
Stupidity: After Jaden summons EH Tempest, he also activates the field spell Skyscraper. This means that Tempest gains 1000 attack points (going from 2800 to 3800) when it attacks Dark Guardian (whose attack points are 3800). Since Dark Guardian can't be destroyed by battle, Jaden sacrifices a card to keep Tempest on the field. What was Jaden expecting? He already knew about Dark Guardian's effect, and there would've been no life point damage, so this attack wouldn't have benefited him in any way.
Tag Team Trial: Part 2 - S1-E11
Stupidity: After Jaden summons Elemental Hero Sparkman to the field, he also activates the spell card Spark Blaster, which he equips to Sparkman so that it can change any monster on the field in attack mode to defence mode. He decides to switch Gate Guardian to defence mode, however, he could have also switched Defence Wall to attack mode as well. Then he would've been able to have Sparkman attack Defence Wall, and it would have been destroyed since it has 0 attack points.
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)
Tough Love - S2-E43
Stupidity: When Syrus beats the Obelisk Blue student, the student throws him his GX medal. When this happens, the two are standing on rocks in between the ocean, and could have risked the GX medal falling into the ocean when it was thrown. It would have just been easier for him to hand Syrus the medal personally. (00:00:32)
Tag Team Trial: Part 1 - S1-E10
Stupidity: Para uses a spell to summon Suijin (2500 ATK), he sacrifices Kaiser Seahorse to summon Sanga of the Thunder (2500 ATK). Then sacrifices those two monsters, along with Kazejin (2400 ATK) to summon Gate Guardian (3750 ATK). He then has Gate Guardian attack Steam Gyroid causing Syrus to lose 1550 points. But if he had attacked Steam Gyroid with one of the monsters he already summoned, then attacked directly with the other, Syrus and Jaden would have lost significantly more life points.
Duel Distractions: Part 1 - S1-E36
Stupidity: When Bastion shouts during the duelling exercise, Syrus and Chumley fall over and drop their cards. About 15 seconds later, Chumley stands back up, but leaves some of his cards scattered on the floor. First, his cards could have got dirty or damaged, so Chumley deciding to leave them on the ground is very foolish. Second, Bastion doesn't seem bothered that the cards are still on the ground, despite the whole point of the exercise is about being ready for duelling. (00:04:05)
Stupidity: When Crowler goes into the chicken coop, he leaves the door to the coop wide open. Leaving the door open could have risked the chance of the chickens running out of the coop. (00:00:20)
Stupidity: When Jaden is preparing for the school duel, Syrus, Chumley, Alexis and Bastion approach him with cards that he could use for the duel. Syrus offers Power Bond, however, this card can only summon Machine-type Fusion monsters, and Jaden doesn't have any Machine-type Fusion monsters in his deck, making this card useless to him. (00:03:07)
