Fans of The Responder spotted a blunder immediately after the start of the third episode.
The Liverpool-set thriller has been written by former Merseyside Police officer Tony Schumacher and debuted last week to widespread critical acclaim.
The five-part series follows Chris Carson, a morally compromised urgent response officer tackling a series of night shifts on the beat in Liverpool.
READ MORE: BBC The Responder character inspired by EFC player
Martin Freeman stars in the lead role - and the 50-year-old actor's Scouse accent has been singled out for praise from viewers.
Episode three was broadcast last night and continued to follow Chris' struggles after he retrieved the missing drugs at the end of the second edition.
The episode started as Chris awoke from another tough night shift and was wracking his brain for whether he should return the stash back to the police.
However, viewers were distracted as they spotted the time on Chris' alarm clock shifted from the 12-hour to the 24-hour clock.
Steve said: "Just watched episode 3 of #TheResponder. It’s getting good! Great acting from Martin Freeman. One faux pas , bedside alarm clock read : 3:20 . Next clip seconds later, reads 15:10. So goes back ten mins and turns itself into a 24hr clock!"
Richard added: "Why does Chris decide to change his clock from 12h in Ep1 to 24h in Ep3. Presumably just a continuity fail? #Responder (Loved the series)"
After a harrowing appointment with his therapist, Chris eventually decided to concoct a plan to offer the haul back to Carl for £30,000.
The character was trying to arrange the deal while trying to juggle his turbulent family life after his wife, Kate, asked him to pack his bags.
The edition ended in thrilling fashion after Chris' attempts to hand the haul back erupted in chaos when Carl was stabbed after the drugs were discovered to actually be washing powder.
Viewers flooded the show with praise following the dramatic finish.
Ceri said: "Absolutely brilliant episode 3 of #TheResponder - not an easy watch but perfectly pitched and acted, dark humour and OMG moments! #martinfreeman is fantastic!"
Gill posted : "Yet again sitting on the edges of our seats Brilliant @tonyshoey #TheResponder"
Ewan commented: "#TheResponder is seriously good television"
Natalie added: "Ooooh 3rd episode down of #TheResponder, the cast is great & loving Martin Freeman’s work. Knew something was going down lad."
The Responder continues at 9pm on BBC One on Tuesday and Wednesday (February 1 and 2).
All episodes are also available on BBC iPlayer.
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