I'm a boy science adventurer
The sword almost certainly wasn't a katana, but Earl probably doesn't know any better. And even if he did, it's hard to get a good look at a blade when it's jammed under your chin.
I mean, I assume it is. I'm not speaking from experience, here. (Fortunately.)
The second season of Venture Bros. is over! I got into this cartoon very recently, and plowed through the entire thing just in time for the airing of the season finale. It's a brilliant parody of Johnny Quest-like cartoons and superhero comics, but the part that makes it really endearing is the utterly fascinating universe it takes place in (and the joyfully vicious sense of humour it employs.) Heartily recommended!