Towards the end, in the news banner you can see: "Reports Continue of Mysterious 'Air Vent Monster'." It is a reference to the previous episode "Cooperative Calligraphy" (208) where it is revealed a monkey is stealing items and living in the air vents.
According to the ages given in this episode Jeff was born in 1978, Annie was born in 1992, Magnitude was born in 1994-1995 and Pierce was born in 1945, which is later confirmed in the season 3 episode Regional Holiday Music. However, not only does Magnitude look older than 16, the age given in the episode, but his intellect level doesn't reflect that of a 16 year old genius, or why he would be attending Greendale of all schools if he were a genius. Annie is also given the age of 19 in this episode, which would make her born in 1992; however, in Mixology Certification, she says she was born in December 1990.
The trivia item below may give away important plot points.
The Greendale Closed-Circuit TV channel crawl at the bottom of the screen mentions various previous and future episodes including that Professor Slater from season 1 is still missing. Also mentioned on the crawl is that there will be no paint balls at the school and that the spring picnic will be western themed a reference to the two part finale at the end of the season.