Episode #3.1 - S3-E1
Audio problem: Camille invites Humphrey to have a drink with the crew. When he begins to say that "It'd be a bit awkward", Kris Marshall's lips don't match the audio in the brief cut when the camera is slightly behind him. (00:50:25)
Continuity mistake: When Aunt Mary is writing on the whiteboard at the hospital, the word "killed" changes style between shots. (00:31:40)
DI Jack Mooney: My grandfather told me a story once, about these two wolves fighting inside all of us. And one of them is anger, envy, self-pity, regret. The other one is love, truth, faith, hope, that sort of thing.
And I asked him "which one of the wolves would win?" And do you know what he said?
"The one you feed." (00:18:15)
In the Footsteps of a Killer - S6-E7
Trivia: In the close-up of the diary of Julie Matlock, you can read in the column to the right of the page with the mysterious number 19871 a name; Agnes Dahan. It's the name of the production buyer of the episode, and long time staff member of the show in production and art department. (00:20:20)
Question: Why did the cord on the wall phone in the police station change from straight in the early episodes to coiled later?
Answer: There's probably no particular reason. Sets and props on long-running TV shows often change as needed and for various reasons throughout a series run.
raywest ★
As long as such changes aren't an obvious continuity mistake (e.g. changing multiple times during a day), one can just assume the change happened in-universe as well. Things do get broken or updated occasionally. It adds a bit of realism, in my opinion.