Just some random silly non-official Saladin animated series doodle/fan art. What they are laughing at, I don't really know; Probably a prank they pulled on Duncan (who is either too confused or not amused with the result).
Also, this show is recently nominated for an Emmy award (Children and young people category). Congratulations and well done to the people involved in the project!
*EDIT (17/October/2011)* Article: Saladin to hit global market