Jorge Garcia confirmed on his own podcast that he added in Hurley's line where he asks Richard Alpert if he's a "vampire". Garcia wasn't sure if the line would be left in, but to his own surprise, it was.
On the wall of Principal Reynolds's office there is a large photograph of what appears to be a scenic shot of the island.
In the classroom, Linus is teaching the students about the island of Elba, which historically has several similarities to the Lost island.