These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Alternative Character Interpretation / Depending on the Writer: The second prince in Japan and overseas. As "Sumaltria" (Japan), he's said to be "a slacker, a drinker, and an overall really fun guy". "Cannock" (Overseas) is a "studious young man immersed in his studies" and "easy-going", "doesn't like to hurry", and "[makes] side-trips".
Breather Level: In a strictly-design sense, the last dungeon is stupidly easy to navigate. Everything else about it though? Well...
Demonic Spiders: The final area of the game contains enemies called Gold Batboons (Bat Demons in the GBC version) who could potentially wipe out your party in one turn with their Sacrifice spell. Sacrifice, when used on you, results in a total party kill 100% of the time. The only other enemy in the whole series that can use this ability is the Rockbomb, but at least the Rockbomb waits until you've sufficiently provoked it before casting the spell. Gold Batboons can choose to do it on their very first turn if they're so inclined.
It should be mentioned however that Gold Batboons really only appear in the final section of the overworld, and right where you can save as well. Typically if you are hit by their Sacrifice spell, it'll only be when you're grinding here, and since you don't lose your experience when you die (which is what is really important at this point in the game), and thus don't really lose your progress either (you're sent right back to the shrine on the overworld here where you've saved), it's little more than an annoyance. If they appeared in the middle of the final dungeon crawl, that would be a different story.
Just about anything in the second half of the Cave to Rhone qualifies. Dragons have a breath attack that has the potential of critically wounding or killing two thirds of your party if you don't level grind. Flames usually come in a group of four and can cause a Total Party Wipe if they all use a breath attack that deals about 35-40 damage. There's a reason why Cave of Rhone is That One Level and why the game's generally considered Nintendo Hard.
Ensemble Darkhorse: While never addressed in canon or other games, quite a few fans are fond of the Princess of Cannock, making up little stories and fanart for her. She did get something of a role via an Expy in Kiefer's sister, Leeza, in Dragon Quest VII, but the personalities of these two are quite different.
Goddamned Boss: While Hargon isn't too hard, he has the penchant of casting Healall at the worst time possible, fully healing himself. This is especially annoying on the NES version, when he has about 200 HP and can fully heal himself, which essentially restarts the battle for him (and not for you).
Hence why casting Stopspell on him should be part of your strategy.
Memetic Mutation: In a somewhat literal sense, Fan-Art of the Princess of Moonbrooke sometimes gives her dog-like traits or a tail and ears, due to her transformation.
That One Final Boss: In a series of relatively tough to just plain hard bosses, Malroth is just plain cheap. As of this moment of typing, he's the ONLY Dragon Quest final boss to have Fullheal. Not that bad in the NES version, as he only has 250 HP, but in the remix? He's got SEVEN times that much. Even if it doesn't heal all 1750, 999 is a real "up yours" to the effort you just put into knocking that off him.
YMMV on the NES version being "not that bad". 250 HP is a pretty big amount in this game, and unlike Hargon, who will only use Heal All when near death, Malroth can use it whenever he feels like doing it. Depending on how frequently he uses the spell, it can lead to an Unwinnable situation, especially since Malroth dishes out more damage than any other enemy in the game.
Frankly, Bazuzu and Zarlox can potentially also spam Healall if you're incredibly unlucky. Atlas is the only one of the five final bosses who doesn't have Healall, and Hargon is the only one of the five that you can silence with Stopspell. That said, in all my many years of playing this game, this troper has never seen such an unwinnable situation happen with any of these bosses.
That One Level: The road to the Rhone Plateau is full of pitfalls, tough monsters that will decimate your party if you come in at a low level, and a section at the end where it will loop if you go the wrong way. This stands out among of a handful of reasons this game has a reputation of Nintendo Hard.
Woolseyism: Laurasia was called "Midenhall" in the original NES port, perhaps to better jibe with the vaguely Saxon/Nordic names used in the first game.