Episode #2.3 - S2-E3
Character mistake: DS Maxwell comes to Katy's house to interview her but when he introduces himself he says "DI" Maxwell.
Liar (2017)
1 character mistake in season 2 - chronological order
Starring: Joanne Froggatt, Richie Campbell, Danny Webb
Factual error: Everyone, including other police officers, addresses the detectives as "Detective" rather than using their ranks of "Inspector" or "Sergeant" as they actually would.