In the DVD commentary for this episode, director James Contner says that while filming the scenes with Willow and Xander on the cliff, the wind churned up dust, which blew into Alyson Hannigan's eyes. Because of the dust, Hannigan removed her black contacts and her eyes were blackened digitally in post-production. See more
The first day of kindergarten you cried because you broke the yellow crayon and you were too afraid to tell anyone. You've come pretty far; ending the world, not a terrific notion, but the thing is, yeah. I love you. I loved crayon-breaky Willow, and I love scary, veiny Willow. So if I'm going out, it's here. You wanna kill the world, well then start with me. I've earned that.