Steve Howey (Kevin) started the season with a cast because he snapped his Achilles tendon in real life, so the writers just wrote it into the show.
When Lip, Mandy, and Ian are registering for the competition, the guys running the registration table are wearing shirts with the oath of the Night's Watch from the show Game of Thrones.
In this episode viewers learn that Lip's full name is Phillip Ronan Gallagher.