Blooper/Corpsing/Hilarious Outtakes: When Matt laughs far longer than necessary at a witness' idiotic comment and eventually turns away from the camera to compose himself, it's obvious that it's Jamie Bamber himself cracking up, especially since the straight-faced Ronnie continues questioning the witness as if nothing has happened. Ironic, as it's Bradley Walsh who has the comedic background. In fact, most of the outtakes involve him causing the second trope to happen to the other actors in the scene. In one clip he specifically asks "Did he go?", referring to Bamber, indicating that he deliberately said something to make him laugh.
Fake Irish: Subverted. Jamie Bamber was born in London, but has Irish ancestry and citizenship thanks to his mother. Matt reveals his Irish heritage to a young prostitute he's interrogating and states that during his rookie year's he was "called mick for the first 6 months because my family are Irish", but his background is slightly different—in an interview, Bamber described Matt as being from "an immigrant Irish family" indicating that he was born in Ireland and then emigrated to England.
Bill Paterson once appeared in a mini-series called Criminal Justice as a policeman. For added irony, he called the Crown Prosecution Service "the Can't Prosecute Service."
Dr. Moon has shown up as a defense attorney several times, most infamously as that for Matt's killer.
Irony as She Is Cast: Matt butchering the French language when trying to talk to a witness when in Real Life, Jamie Bamber speaks excellent French (aside from an early childhood spent in Paris, it's one of two languages, the other being Italian, that he studied for his Modern Language degree).
Keep Circulating the Tapes: Only Season 1 (Series 1 & 2) and Season 2 (Series 3 & 4) have been released on DVD in the US. To watch the remaining episodes, which have been released in the UK, anyone in Region 1 will need to either (a) purchase a universal DVD player, or (b) scour the internet. Luckily, Series 5-7 are readily available, but so far, you seem to be out of luck if you want to watch Series 8 in any format—it hasn't even been aired on BBC America as yet.
McLeaned: Matt Devlin was killed in a drive-by shooting when actor Jamie Bamber finished his contract; at the time he was doing a pilot for a US show which was not ordered to series. The writers probably wanted to kill off a major character to provide good drama, so it's a pretty classic example of Reason #1 for this trope — the following episode was one of the series best as the team struggled to deal with their grief while doing their best to ensure that his killer was brought to justice.
Playing Against Type: Walsh is a well-known comedic actor and game show host who was thoroughly impressive as Brooks.
Too Soon: Because its plot bore considerable similarities to a Real Life murder that occurred the day before it was scheduled to air, the Series 8 finale "Repeat To Fade" was pulled from the schedule and replaced with a Season 5 repeat. It took nearly a month for it to be rescheduled.