Other mistake: When Lucy is in the cafe watching the mother and her children, the mother repeats the same dialogue.
Plot hole: Tahnee was sent to boarding school when she got fired as a way to get her out of the show, but she was 17 and so isn't that a bit of a silly way to write her out? In Melbourne Australia, you can leave school if you wish at 15, so she in theory shouldn't be able to be forced into going to Boarding School.
The Murder's in the Mail - S1-E6
Factual error: Dead blonde guy is sitting upright in the chair, as Dave/Maddie close in, and Maddie realises he isn't moving. David goes to him and smacks him across the shoulder, to "wake him up" and blonde dead guy, right on cue, instantly slumps over a table at his right side, when the direction that David hit his shoulder, should have sent the dead guy slumping more forward, then at the front edge of the table. Obviously staged for the actor's comfort.
Continuity mistake: Multiple times throughout the show, Kimber can be seen in quick shots with light pink hair (the same color as Jem's), when her hair color is actually a dark pink/red color. (02:00:00)
The Town Where No One Got Off - S1-E4
Visible crew/equipment: The overhead boom mic dips into the scene as the old man is speaking.