Here's a short video with the crew in attendance. I talked with them after the panel back stage, they're are a nice but shy group of animators, the voice talent is a bit more brave.

After showing some future episodes and a animatic featuring Jake's old crew, the audience laughed there guts out. Then the crew fielded question after question mostly about when old one time characters would make another appearance. It was discovered that Pen Ward didn't want Tiffany back in a future episode, but that made the crew want to bring back him back even more. Germaine, the brother of Finn and Jake was just an after thought for Jesse Moynihan, his creator, who felt some what pained now to have to bring him back. Adam Muto and the rest of the crew said they'd bring back characters only if felt organic. They never just have episodes for that character to appear in without reason.

In return the AT crew was given it's own special gifts like a picture of a dinosaur to be put in an episode and a Bratz doll made to look like Fin even a song ballad
The question about a movie came up again and the crew would love to do it, but nothing more than that was answered, so it's still a fan dream until Pen really gets behind the idea.
Fionna and Cake shall never meet Finn and Jake! At least not on television, maybe comics. Adam Muto seemed to make it very clear that there are no ideas of how they would pull it off without it being boring, he said all they have right now would be them saying hi to each other and that's not good enough.

They stumbled through a lot of it, but with there nervousness made the audience relaxed even when a slight video malfunction forced the voices of Beemo and Flame Princess to act out the clip that was suppose to be shown.
As I already posted anyone in attendance got a wonderful Adventure Time poster for showing up.
Though Pen wasn't there the crew could share how he's artistic vision spreads over them. Mostly it seems whatever Pen does in video games will make its way into the show.