If you look carefully, each episode contains a randomly placed image of a pickle,
Snoop Dog was featured in an episode at one point.
Almost every, if not all, episodes contain an image of Huggle Bunny(i.e. in a picture, in character, etc.)
Lundgren, the town where Sanjay and Craig live, was confirmed in the Christmas special to have been named by the famous actor Dolph Lungren, who guest starred in the special.