Happy Valley viewers were quick to point out the 'obvious' blunder as they tuned into watch Sergeant Catherine Cawood take on her final mission, which saw her have one last showdown with dangerous crook, Tommy Lee Royce.
BBC One viewers couldn't quite believe show writers had missed such a pivotal part to the story as they watched in horror as Tommy Lee broke into Catherine's home, where he attempted to end his life with a concoction of pills and alcohol.
The chilling scenes saw the escaped killer, who had raped Catherine's late daughter, sitting at her kitchen table flicking through her family photo albums with the pills and booze alongside him.
Sergeant Cawood arrived back to her home to see her window smashed in, and viewers watched in anticipation as the Yorkshire crime fighter bravely headed inside to see Tommy Lee sitting at her kitchen table.
It didn't take her long before she drew a taser at the escaped killer, putting an end to the heartache once and for all.
However, as eagle-eyed viewers watched the drama unfold, several took to Twitter to point out an obvious blunder.
Given that Tommy Lee was a wanted man, and given that he had beef with Catherine, viewers questioned why her house wasn't under 24/7 surveillance.
"Would they not have had somebody watching the house if they knew he was after her?" one fan questioned.
"Surely Katherine’s house would be under police surveillance," another echoed, while someone else pointed out: "Hmm, broken window at my house. Escaped murderer on the run. I know I'll just enter the house for a sneaky look around without letting anyone know. Ffs come on. This is b*******."
"Sorry but her house would definitely be under watch. What a blunder," another Happy Valley viewer complained.
Elsewhere, others complained that when Catherine raised the alarm, assistance seemed to be taking too long.
"How long does it take the police to get to catherine’s house ?!?! Pressed for time here people chop chop," one viewer quipped.
"She's an officer and there's an escaped KILLER ON THE LOOSE!! Surely it wouldn't take long for police to arrive," another echoed.
It comes as Happy Valley fans are praying the show will return for a fourth season, despite producers previously declaring Sunday night's finale was the very last episode.
BBC viewers say they have unanswered questions following the crime drama's nail-biting conclusion, which saw Catherine (Sarah Lancashire) come out alive during her final showdown with Tommy Lee Royce.
