Donnie Darko (2001)

Continuity mistake: When Cherita makes her mark on the lifeline blackboard, there are some smudges on the broad chalk line. In the next shot, the line is perfect again. (00:41:30)

Phoenix

Donnie: You are such a fuckass.
Elizabeth: Did you just call me a fuckass? You can go suck a fuck.
Donnie: Oh, please, tell me Elizabeth, how exactly does one suck a fuck?

Trivia: The time when the world is supposed to end is 28 days, 6 hours, 42 minutes, and 12 seconds. 28+6+42+12=88. The year the film takes place is 1988.

Question: In the part of the movie when the science teacher and Drew Barrymore are sitting in the staff room, what does their conversation mean? Science teacher says, "Donnie Darko." and Drew Barrymore says, "I know." What significant plot does this have?