Continuity mistake: Celeste and Madeline are in the car and greet Bonnie, who's hiking. In the immediate shot of the copilot mirror's reflection Bonnie is nowhere to be seen.
The Gang Tries to Serve a Subpoena - S4-E2
Continuity mistake: Luca and party are about to board a green private jet. Moments later when they take off, the shot shows the forward underside of a white plane. At first I thought that maybe it was white on the underside, but the nose wheel well doors are indeed green, and the takeoff picture shows an airplane with white nose wheel doors. (00:19:40)
Factual error: When Detective Inspector Sara Lunt's photograph in uniform is shown on the TV news she is wearing a double row of silver lace below her hat badge. Only chief constables wear this insignia, well above the rank of inspector.
Deliberate mistake: The police force in the town is the Gendarmerie, the standard issued firearm is the Sig Sauer P2022 in 9mm. The police officers on this show carry a Beretta and not the 9x19mm one which is the model 92fs, they carry a never issued Beretta 84 chambered in .32 acp or 9mm short. Plus they use some weird holster where the gun arches out and hangs low like a cowboy holster and dangles around. Easy for a suspect to gain control of the officers gun and this happened in this episode.
Episode #4.9 - S4-E9
Factual error: Renate escapes from the prison in a Morris Ten Four, with the badge visible on the bonnet. However, this designation was not introduced until 1935 and the episode is set in 1931.