I don't want to go too far into auteur theoretical perspective, but I think the slideshow really shows off Pendleton Ward's authorial sensibilities well. Supposedly Pen brought a guitar began his pitch by singing, a first for the executive Fred Seibert who had seen about 2000 pitches by then. He also described the show foremostly in terms of the relationships the characters have which was a rad move in my book.

There's an amazing concept art for the tree fort. Have I talked here before how much their tree fort rules? Yeah it's the best home in all of cartoons. Disagree only if you absolutely have to.

I remember people disliking the loosey-goosey nature of character animation and design back when the show was a pop culture phenomenon. Honestly I think the pitch shows how expressive it can be. When you get abstract and cartoony enough, roughness of line and freedom of proportion can really make it feel concrete again. The "Finn and Jake Moments" of page 13 would be so dull and boring with realistic joints and more detail. Here's a legendary Tumblr post making the same point.

As the last but not the least, there's two pages worth of fan art. Such a sweet gesture, isn't it?