At a screening in San Francisco, director Bo Burnham said he originally intended for all the young characters to communicate with one another over Facebook. When his star, Elsie Fisher, saw his script, however, she said, "No one uses Facebook." He then made that a line in the movie and had the characters use Instagram and Snapchat instead.
Speaking on Marc Maron's WTF podcast, director Bo Burnham said that technology company Apple was going to provide laptops and phones for the film for free, but they were unhappy with the scene where the iPhone broke when it got thrown. As a result, the laptops shown in the film were those belonging to the crew and the broken iPhone scene was kept in.
On the Jimmy Kimmel show director Bo Burnham reveals that after star Elsie Fisher finished filming for Eighth Grade she started her first year of high school, where she did not receive a part in her school play.
Bo Burnham deliberately made his protagonist a young girl because it avoided easy comparisons to his own career trajectory beginning with YouTube videos, and because when doing research into vlogs by young teenagers he noticed, "The boys talked about video games and the girls talked about their souls."