The theme tune that persists throughout the series. Whenever it's sung, it takes the portion talking about "masked heroes hiding righteous hearts". Normally it would be just a snippet of the original tune, but its use actually alludes to what Leopard, Elephantus and Voltkatze become. The Yattermen's corruption spurs about Leopard's desire to stop the Yattermen from ruining the lives of innocents, showing her own righteous heart. The "Masked Heroes" bit is obvious.
Also, the song exists as a song passed down the generation from the first Doronjo to Leopard through Dorothy. And Doronjo was likely to know about Dokurobei's plans, since they involved giving her the ultimate punishment - exile for her and her descendants, for failing to win against the Yattermen and forcing Dokurobei's hand. So, she subtly gave her descendants the means and the will for searching the Yattermen, and seek the truth for themselves.
During the Triumphant Reprise in Episode 12, the cue for the original intro theme to start is Galina, as Yatterman 1, cranking up Yatterwan, followed by him howling. In the original 1977 intro, the first scene in the credits... is Yatterman 1 cranking up Yatterwan, followed by him howling. They actually did a reprise of the original audio cues!!!
Voltkatze and Elephantus giving Takeshi the snow bunny in episode 5. They both know what it's like not only to be poor, but also to have someone you care about get sick. So, coming from experience, they want to have Takeshi's mom have as much joy and laughter as she can before she can succumb to her illness.
Some relating to the Genius Bonus in episode 6: it's shown that whenever General Goro tries to remember anything about Alouette, he briefly shuts down- invoking the "silence" meaning of lavender. In addition, the fact that Alouette is so willing to find her parents even though there's a huge possibility that they might be dead lingers onto the "devotion" meaning of lavenders. The two ideas converge on more than one occasion when the two meet in Episode 6 and onwards since she starts to wear lavender in her hair more often, hinting at a strong connection between the two.
Yatterwan was made from Wan-chan's core parts, meaning that Yatterwan is the Yatterking to Wan-chan in this series.
Combined with Fridge Horror in the next section: in the end Yatterwan is, once again, retooled to be closer to the original Yatterwan and Alouette leaves behind the overpowered Shock Stick inherited by her father. The Yattermen and Yatterwan were never meant to be tools of war: Galina needed a stronger Yatterwan, needed a stronger Kendamagic and Shock Stick, and needed to fortify himself enough to kill Dokurobei and the Guardian Gods. In the end, he and Alouette divest themselves and Yatterwan of every lethal weapon, embracing their roles as a "mere" beacon of hope.
Added to this is a bit of Fridge Logic. They just eliminated a despotic ruler claiming dominion over the world in 'their' name. For them to publicly return to being peace-keepers instead of warmongers is a massive step in the right direction.
Again about Yatterwan being Wan-chan: in the 2008 Yatterman's series Yatterwan has a marked preference for the sweet and good-natured Ai. As Wan-chan, this preference becomes utter devotion to his beloved owner.
A bit concerning the show's title. An alternate way to translate it is "Dark Yatterman", which works on two fronts- one for the protagonists of the story, who disguise themselves as villains, but are actually a force of good within the story (essentially "Yatterman"-like characters on the "dark" side). The other relates to Lord Yatterman, who oppresses the people he ought to be helping out, making him the opposite of what Yatterman is supposed to represent (being associated with "dark" deeds).
This can be seen as clever but while the Big Bad Dokurobei uses the name of the heroic Yattermen for evil, the main protagonist and hero Leopard uses the name of her villainous ancestor Doronjo for good.
While life in the post-apocalyptic wasteland outside the wall is certainly harsh, impoverished, and of low expectancy, Leopard quickly discovers that life within the brutally oppressive Yatter Kingdom is no improvement whatsoever, the word "Hell" being used on more than one occasion. By exiling the Doronbo Gang's descendants to the wasteland, Dokurobei - perhaps for old time's sakes (and we know he is not immune to sentimentality, as he does offer to conditionally spare them in the finale) - shows them about as much mercy as one could ever hope for in the twisted world he has created, at least allowing them to live without the constant risks and humiliations of the Yatter Kingdom citizens who seem almost as impoverished, in any case. Of course, it also keeps the most likely troublemakers to his regime at a safe distance (but then again, he could have just wiped out their bloodlines rather than exiling them, had he not felt a little touch of fatal nostalgia).
Galina's parting salute, particularly with the Doronbo catchphrase ("Ara hora sei sei"), to Leopard / Doronjo, as the new "Yatterman-1", while heartwarming, beautifully underscores one of the main ironies of this series: Gan, Ai, and the "Yatterman" franchise itself pretty much owe their purpose in life and their continued existence to Doronjo and the "terrible trio". Without her, all that is left are hollow, silly-looking symbols. Doronjo and her loyal lackies make "Yatterman" what it is (and of course, within the context of "Yatterman Night" itself, they literally do create the new Yatterman duo, inspiring Galina and Alouette and providing them with the skills and motivation to finally lead the resistance).
The original Doronjo apparently speaking to Leopard in her sleep, at the conclusion, raises the question of whether the spirits of the Doronbo Gang's ancestors have in fact been watching over their descendants all along, which would certainly help to explain why Voltkatze, a realistically competent technician, becomes a deranged one-man robot factory when "channelling" Boyacky, and Elephantus, a tough farmhand with zero field combat experience, becomes a battlefield powerhouse in "Tonzura mode."
While No Fourth Wall is downplayed in "Yatterman Night" compared to the host series (where it was so lax that characters could argue with the narrator, berate each other for wasting the budget, and get into humiliating losing fights with their own real-life actors), it is still the "rule" as shown in episode 11, when Dokurobei uses an old Yatterman VHS tape in lieu of historical records. This makes the whole serial in a sense a sardonic joke at the viewer's expense. Since Dokurobei, when "punishing" the original Doronbo Gang (usually very unjustly), would often claim that he was mainly doing it to satisfy the viewers' lust for sadistic slapstick rather than his own, he could very well be seen as the unsung hero of "Yatterman Night", through his (appalling, apocalyptic) actions giving the viewers something they have desired but was not possible within "Yatterman" itself: namely a world where the Doronbo Gang could at last be the front-and-centre good guys, and finally get to give the Yatter forces a good forehead-flicking. It's just an unfortunate technicality that world needs to be a screwed-up dystopia (but hey, fanservice ...).
Combined a bit with Tearjerker, but in episode 9, Galina and Alouette encounter the Mach 5 and it's guarded by Sanpei/Chim Chim from Mach Go Go Go / Speed Racer... Does anyone stop and think that what if at some point the Yatter-Soldiers might have done something horrible to Speed, Sprittle and Pops Racer and that's why the monkey's guarding the car until they come back? That poor monkey...
A tiny bit from the finale. It was undoubtedly awesome to see Galina use the new and improved Kendamagic on one of the Guardian Gods, even blowing him up with electricity. However, Word of God states that the Guardian Gods were Cyborgs, just like General Goro. Take that in for a second. Galina just killed a man. Someone who could've been just as innocuous and kind as Mister Gorozo, gone. Especially since all of their memories have been erased by Lord Yatterman.
See above in the Fridge Brilliance section, but Galina keeps a grim, expressionless face during the whole ordeal. He didn't want to kill: he was forced to, and had to heavily weaponize the Yatterman legacy to prevent Dokurobei from further slandering it. Also, notably, it's implied he disabled as much of it as possible once Dokurobei was eliminated.
Amidst the general light-heartedness of episode 9 with its sentient chimp and robot-car-from-another-cartoon, there is a surprisingly dark climax as Abareshi Prison is blown up by the Yatter mecha crashing into the reactor, as an indirect result of Galina's rescue attempt. While the Doronbo Gang survive (safely riding out massive explosions runs in the family), no mention is made of the unfortunate Yatter Kingdom inhabitants imprisoned as slaves within it. While this could count as a rather grim mercy, since Abareshi was not far off being a death camp for dissidents, it is a little disturbing how quickly it is glossed over.
