Captain Crash: Jean again, though this one's not his fault (as the plane gets hit by Neo-Atlantean weaponry and there was only so much he could do).
Contrived Coincidence: Jean and Nadia arrive at Cape Verde at the same time the Grandis Gang have made port. However, this can be justified in-universe as Hanson stated last episode he was going to chart a course to the nearest island. The kids were also only aboard the Nautilus for 3 days as Nemo tracked the Garfish that attacked the Abraham (which we know now was heading back to base at Cape Verde). So, it makes sense that both the kids and the Gang would be in range of the island at relatively the exact same time.
Due to the Dead: Nadia and Jean take time to bury Marie's parents and dog.
Game Changer: After their quiet supporting role in Episode 4 (and even Episode 3), Neo-Atlantis is formally introduced. Their introduction will change the narrative trajectory from children evading jewel thieves to a global Secret War. The stakes are also upped with Jean and Nadia nearly dying and the murders of Marie's parents.
Know When to Fold 'Em: Upon being surrounded and outgunned by Neo-Atlantean soldiers, Grandis orders the Gang to surrender. She knows she, Hanson, and Sanson won't be able to fight their way out this (yet, anyway).
Malevolent Masked Men: The Neo-Atlanteans, although their names aren't given until next episode.
The Nameless: In this episode, there's no information about the name of the higher villains.
Electra, on Nemo's orders, sent Jean and Nadia to Cape Verde without realizing that the island had been forcibly taken over by Neo-Atlantis.
Inverted with Nadia asking Jean to circle the island first before coming in for a landing. While she suggested this because she was (justifiably) worried about Jean pulling a Captain Crash again, this arguably ends up saving their lives. If they had come in on a direct approach rather than circling Cape Verde, the Neo-Atlantean anti-aircraft batteries would've been able to hit them head on instead of a passing blow and they all would've died instantly.
Villain Respect: When the Grandis Gang think Nadia and Jean died in the crash, they take a moment to pray and mourn, then try to check whether they might have survived or not.
Wham Shot: The Grandis Gang being surrounded and shot at by Neo-Atlantean soldiers. What, did you actually think the proto-Team Rocket in the funny steampunk tank were the real bad guys of Nadia?
