Best comedy TV mistakes of 2017
Continuity mistake: When Deborah is talking to Mrs. Chadwick, Mrs. Chadwick's hair keeps changing position and is either covering or not covering her name tag. And when the camera is on Deborah, we still see Mrs. Chadwick's head and she doesn't move it at all.
Continuity mistake: Earlyish in S1:E4 "Growing Suspicion" there is a still photo of Christa Carlyle wearing a cast on her broken right leg. Early in this episode there is a quick motion shot of her handing out a T-shirt to another student. The cast is now on her left leg.
Audio problem: Right after Carol finishes studying by singing a rap to Katie, Katie congratulates her and Carol hurries out. They exchange several lines of dialogue, but it all appears to be dubbed. During most of the dialogue, each character's mouth is not shown when they speak. However, the cadence of Katie's moving jaw can still be seen from behind, and appears to last longer than the audible speech. Additionally, Katie and Carol can each be heard to speak when it can be glimpsed that their mouths are not moving.