Writers Seth Rogen and Evan Goldberg started this script when they were just thirteen years old, because "we just wanted to see if we could write a movie."
During filming, Christopher Mintz-Plasse was the youngest at seventeen, Michael Cera was eighteen, and Jonah Hill was the oldest at twenty-three.
Michael Cera's mother actually read the script before he did, and she was the one who convinced him to try out for the part.
Because Jonah Hill and Seth Rogen are such great friends, they were quoted as saying that when casting Evan, they weren't so much looking for a good actor, as they were "casting for a new best friend."