Flaming Sword: The second most powerful weapon you can wield. The best one is Erdrick's sword.
Getting Crap Past the Radar: In the first town, you can meet up with an ardent female admirer who will "tag along." If you spend a night while she's with you, the dialog strongly suggests you and the admirer had a night of wild sex. This can also happen while you are escorting Princess Lora. (In the GBC and mobile versions, you can actually spend the night at the inn with both of them in tow!)
Orcus on His Throne: The Dragonlord pretty much just sits in his castle all game and waits for you to come and kick his arse. Justified in that, by all appearances, he doesn't have to move; talking to townspeople makes it clear that he effectively rules the world already, and from his perspective you come out of nowhere.
Playing with Fire: He can cast Hurtmore/Firebane/Sizzle, as well as breathe fire in his true form.
Squishy Wizard: By the time they get to him, most players can kill his first form in three hits.
We Can Rule Together: The Dragonlord makes this offer to you when you confront him. Most players just select no and get on with the battle, but if you accept, you get a Non-Standard Game Over (except in the SNES version where he wakes up in a town near the Big Bad's castle, where the innkeeper says that he had a Bad Dream).