That’s exactly what happened in the latest episode, as eagle-eyed viewers noticed a filming blunder during one scene featuring Steve Arnott (Martin Compston).
It may be renowned for its attention to detail and meticulous plotting, but sometimes even Line of Duty slips up.
Line of Duty continues on Sunday 11 April at 9pm on BBC One.
The official Line of Duty Twitter account even responded to someone pointing out the cameraman, writing: “Or was it…”