St. Shondaland Animal Hospital is a reference to Shondaland, the production company that made Grey's Anatomy. All the scandals happening between staff members at the hospital are also a reference to Grey's Anatomy.
Ralph Wiggum uses a purple crayon to draw a doorway and a staircase on a wall; it turns real, and he goes up the staircase. During the post-credits, Chief Wiggum tries to coax Ralph out of the hole, but he draws a sailboat and keeps going deeper.
The Itchy & Scratchy Show episode "The Great British Slaying Show" is a parody of The Great British Bake Off. The judge mice are parodies of Matt Lucas and Noel Fielding who are presenters on the show.