In the climactic scene of this episode, Ofdensen and Melmord both use their swords left handed, but at the end we see them fighting right handed.
As an aside, this makes it reminiscent of the duel between Inigo and Wesley from The Princess Bride.
Health inspector: The conditions down here are repugnant! It's infested with rats, molds, and some strain of flesh-eating virus.
Nathan Explosion: Pretty metal.
William Murderface: Pretty metal.
Health inspector: Oh, is it? Your staff is dying down here. Is that metal?
William Murderface: I hate to say it, but yeah.
Nathan Explosion: Yeah, not to be contradictory, but it's very metal.
Health inspector: Is it metal to have your drains clogged with dead, rotting employees?
Nathan Explosion: Yeah. It is, actually.
William Murderface: Metal.
Health inspector: Is it metal to have easily avoidable work-related accidents that cause of death?!
William Murderface: Yeah. Again, metal.
Health inspector: Is it metal for none of you to care at all?
Nathan Explosion: Yeah, it's way more metal if we don't care about it.
Health inspector: Well... I guess I, uh, didn't know all that stuff was metal.