The janitor on duty while the students are serving detention is named Carl, same name as the janitor on duty while students are in detention in The Breakfast Club.
All three female actors in detention are named Sophia/Sofia: Lillis, Bryant, and Tatum.
While in detention, Stan is shown playing with a Rubik's cube. During a promotional video with Wyatt Oleff and Sophia Lillis, they disclose that solving Rubik's cubes is one of Oleff's secret talents.