Joey Wheeler's deck gets stolen by a kid, but he quickly gets it back. Later, he faces Weevil Underwood in a duel, but finds that his deck has been sabotaged, putting him at a disadvantage. Joey and his friends realize that Weevil hired the kid to sabotage the deck and angrily condemn Weevil for cheating. Weevil confirms this, but retorts that it is Joey's fault for being so stupid and naive that he did not inspect his deck after getting it back. (Especially since he had messed with Yugi's deck on the way to a previous tournament, and they saw it happen.)
Later on in the arc, when Yugi is going to confront Joey/Jounouchi, Kaiba, in the original Japanese, tells Yugi that while he showed him the power of cooperation in the tag duel with the Masks of Light and Darkness, he wonders how much that idea will hold up now that his friend is possessed. In the dub, this is changed to him telling Yugi he won't help him unless he stands to benefit.
Another Kaiba moment would have to be the duel with Dartz where they both were forced to fight the Mirror Knight tokens of their loved ones. Yami is shown to be unwilling to destroy them despite losing to them while Kaiba in contrast, does not hesitate to destroy them and when Yami protests, Kaiba harshly albeit correctly points out that if they are true duelists, they would not hesitate to sacrifice themselves for the world which indeed is proven true when they do so.
During the Virtual World Arc, Lector of The Big Five calls out Kaiba on the way he used and abused both The Big Five, and his own brother, Mokuba, during his coup against his father Gozaburo. While Lector's a bastard, and in no position to criticize, he's not wrong when he points out how unacceptable Kaiba's behaviour was.
In Joey's duel against Rex Raptor in the Doma Arc, the latter gets a good starting hand and manages to summon 3 monsters in his first turn, prompting him to boast about how much stronger he has become since last time he dueled Joey. Joey retorts that he merely got lucky, but Rex immediately points out that's rich coming from someone who only beat him before due to winning a roulette game with Time Wizard. Even Tristan agrees that Rex kind of has a point.
Weevil gets a bigger one later, in the Doma Arc. When Yami tells him he's horrible, Weevil points out that Yami had used the Seal of Orichalcos in order to win despite knowing that he'd be putting his friend in danger, and that Yugi paid the price. Weevil acknowledges that he is indeed an asshole, but points out that at least he didn't use the seal knowing that he could endanger his friends. Even though he tries not to show it, Yami is visibly affected. Granted, the Orichalcos shard that was given to Yami did completely brainwash his mind into playing the card, but from Weevil's perspective, his reaction at least is somewhat justified.
In their first duel, Mai points out to Jonouchi/Joey that even if he and Yugi are friends, there can only be one champion for Duelist Kingdom and sooner or later, they will have to go against the other. She is also right that he has to step out of Yugi's shadow and duel on his own merit if he wants to get anywhere.
In the manga, Duke questions how Shizuka/Serenity is supposed to get over her fears in spite of her eye surgery if she continues to depend heavily on others. Honda/Tristian rebukes him for this but Shizuka agrees with Duke and would be inspired by her brother's actions to gain enough courage to remove her bandages herself.
