- If a Capsule Monster is hurt, so is its owner. When Grandpa's Summoned Skull is destroyed, he screams in pain and collapses. In the final battle, it's implied if all of a person's monsters are destroyed, they die.
- In the first episode, while exploring the pyramid, the group finds a roomful of skulls impaled upon spikes and has to slowly make their way across by hanging from a ledge by their fingers.
- Joey is nearly impaled by a spike trap after he accidentally sets one off.
- In episode 2, Trents attack Celtic Guardian and Yami Yugi, strangling them both with their roots and nearly killing them.
- Yami Yugi shows a little too much glee in having Hinotama Soul burn the Trents.
- Tea and Tristan are cornered by Root Water and stand little chance of defeating it. It grievously wounds Tristan, and when they do defeat it, it evolves into High Tide Gyojin and sucks them both into a whirlpool. Only the timely appearance of Solomon Muto saves them.
- Joey is carried off by a Kurama, nearly fed to its babies, and is chased by a whole flock of them after falling off a cliff.
- In episode 3, a pack of Flower Wolves defeats the group. They pounce on and maul Solomon Muto briefly before Celtic Guardian can throw them off of him.
- In episode 3, Neo Aqua Madoor freezes Tea and Yugi's grandpa in ice, nearly suffocating them.
- Yami and Celtic Guardian are badly wounded when they fight La Jinn, but want to continue to keep fighting despite their injuries. If Joey and Tristan hadn't demanded to help it's unlikely either of them would have survived.
- In episode 4, the statues the group must mimic to open the door turn out to be alive and attack the heroes' monsters.
- In episode 4 Yugi falls through a hole in the floor and ends up in a featureless room... and then the walls start closing in. He comes within seconds of being crushed.
- Episode 5 has Mystical Sand, who conjures up a huge sandstorm that blinds and suffocates the group. Her Medusa Worms turn anything to stone with their spit.
- In episode 7, Joey runs off on his own and is chased by a Red-Eyes Black Dragon. He's later possessed by the Chaos Blade and merges with the dragon, fighting Yami and his other friends.Evil!Joey: Why don't you try worrying about yourself for a change? [blasts Yami]
- The group comes across the edge of the map in episode 8, entering a void of pure nothingness head-first.
- The Five-Headed Dragon is virtually indestructible, and it nearly defeats Yami Yugi with its breath weapon.
- The flashbacks to the waning days of Alexander's reign are very intense. He completely snaps when the door refuses to open, lambastes his vassals despite their attempts to reason with him, and has the Millennium Ring painfully split his soul in two after it claims the lives of his servants while he was unconscious, trapping their spirits in the game.
- Alexander's evil side is reminiscent of Yami Bakura, and the two sides struggle for control of the body. He performs Grand Theft Me on his descendant, Alex Brisbane, and one scene has the two Alexanders' heads jutting out of each other as they argue.
- Alexander sacrifices his own comrades to summon the Seven-Armed Fiend, banishing them from the game. At fist glance it looks like he killed them to summon it.
- Alexander attempts to kill Yugi's Grandpa by having his Seven-Armed Fiend attack him directly with Arm of Destruction.Yami: Don't you dare lay a finger on him!
Alexander: How about an entire hand?
- After the Seven-Armed Fiend's defeat, Alexander uses his vassals' energy to power Reshef so when he is attacked, they take the damage. He then taunts Yami about not doing the same to his friends.
- Whoever wins the final battle would gain the power to conquer the world, which, in the hands of someone like Alexander, would lead the world to ruin.
Nightmare Fuel / Yu-Gi-Oh!: Capsule Monsters