Art Evolution: Nemo and Electra's character models have been heavily redesigned, sporting new hair styles and uniforms (with the latter's uniform very much being a proto-Plug Suit. The rest of the Nautilus crew likewise have received minor tweaks here and there.
Badass Longcoat: Nemo is now sporting one as part of his new look.
Card-Carrying Villain: When Gargoyle inevitability screws over the Grandis Gang, the surrendering Nadia calls him inhuman. Naturally, Gargoyle treats it like a compliment.
Foreshadowing: Gargoyle nuking Tartessos once he has no further use for it — and with it, what's left of Blue Noah, one of the sacred Ark-Ships that brought the Atlanteans to this world. For all his talk about restoring the Atlantean legacy, this foreshadows that Gargoyle's actions will ultimately and ironically bring it all crashing down forever instead.
Genre Shift: The introduction of the N-Nautilus effectively completes the shift transition that began in Episodes 30-31. The original steampunk aesthetics are gone after this episode and the show is now entering Space Opera territory (a shift that will complete itself in the following episode's lead-up to the final battle).
While the Neo-Atlantean airships are overheard, they haven't spotted our heroes yet. The characters decide to carefully and quickly withdraw back inside the city...only for Gargoyle to reveal over loudspeaker the Neo-Atlanteans knew exactly where they were this entire time and they never had a chance at escaping.
The N-Nautilus has the firepower and tactical advantage, they've got Gargoyle dead to rights, and thet can force him at gunpoint to surrender Nadia, right? Well, Gargoyle's still got one more trump card in play...
I Lied: Of course Gargoyle lied about sparing Jean and the others if Nadia surrendered. They outright lampshaded he was gonna screw them, but that doesn't mean they take any joy in being vindicated.
However, it then surprisingly gets averted in the climax. He has Nadia and he doesn't need to keep her alive, but he does honor Nemo's demand to spare her. However, it's Pragmatic Evil (as her Blue Water is still under her control at this point) and because of the propaganda advantages having the lost Princess of Atlantis back in the fold will bring.
Spanner in the Works: Nemo's counterattack and bluff to get Nadia back from Gargoyle fails because he had no way of knowing Gargoyle had Neo in tow, or that his psychic abilities had grown enough to seize control of Nemo's Blue Water.
Spoiler Opening: The Opening is updated to show Nemo, his crew, and the N-Nautilus rather than the original shot of just Nemo and the old Nautilus. Unfortunately, this also spoils their survival and return in this episode.
Surprisingly Realistic Outcome: The Gratan trying to escape Gargoyle's bombardment is slowed down by the cumulative damage the Tank's sustained since the aerial battle in Episode 21. Hanson's patched it up as best as he can (during the Island Arc), but even he could only do so much without access to a garage. The Gratan is only fully repaired with access to the N-Nautilus repair bays in the next episode.
Similarly, when they're falling down one of Red Noah's shafts and the brakes fail, Grandis orders Sanson to just put the damm Tank in reverse. Given their current velocity, Sanson rightfully counters that the ensuing pressure would only cause the gears to blow. The velocity also prevents the tank's cylinders (which Jean suggests deploying as an alternative and which might've worked under different circumstances) from halting their descent.
Where It All Began: Tartessos is this for Nemo and his crew, given their story began here 13 years ago when Gargoyle launched his coup. Similarly, it's one for Gargoyle as well for these same reasons.
Wham Shot: Electra exiting the strange craft, revealing she and the rest of the Nautilus crew didn't perish in Episode 22 and they're here in Tartessos.
The Worf Effect: The N-Nautilus easily takes out one of Gargoyle's flying battleships (which had previously kicked the original Nautilus' ass) to demonstrate how much more powerful this new vessel is.
Wrong Genre Savvy: While it had begun in the previous episode thanks to Nadia's revelations about Red Noah, Jean and the others are finally beginning to understand they're no longer in a Steampunk Action-Adventure story. So they're trying to grapple with being in a genre (Science Fiction/Space Opera) they have no context or frame of reference for it.
You Can't Go Home Again: Tartessos had already been nuked 13 years ago, but Gargoyle finishes the job here and now.
You Have Outlived Your Usefulness: For all his talk about preserving and restoring the Atlantean legacy, Gargoyle has no qualms about nuking Tartessos for good once he gets Nemo's Blue Water. It can be justified, as the destruction of the Tower of Babel wrecked the city and Blue Noah, so anything salvageable was already grabbed when Gargoyle and company left Tartessos 13 years ago. The city being a reminder of how Gargoyle's plans were set back a decade thanks to Nemo also is likely another impetus for nuking it.
