The title of this episode "I know what you did last summer" is also the name a movie (1997) which Kevin Williamson wrote the screenplay for.
When Elena Gilbert is going through the list of contacts on her cell phone, the ones shown are Klaus, Kol, Lauren, Madison, Matt, Pay My Bill, Rebekah, Ryan, Sarah, Stefan, Terri, Tony, and Ty.
Whitmore College is a few hours away from Mystic Falls.
This premiere episode had about 2.59 million viewers in the USA.