If you're referring to "Oh noes!", that's more of a meme than poor spelling.

Personally, I think there aren't enough sites with a personality and sense of humor. I get the point that the very serious career types will not appreciate this, but they might not be Zerply's target audience. I'll also point out that the home page looks fine, nothing silly there. It seems they are just trying to diffuse tension on an error page with humor.