In a newspaper article near the beginning of the episode, the "Oxford Hammer Killer" is named as Graham Lawrie. Later in the article he is named as William Lawrie.
When Hathaway and Maddox are eating in the beginning of the show, the ashtray on the table keeps changing. First it is empty, then there is one cigarette sitting in it, then it is a squashed butt. It then keeps appearing and disappearing between shots.
When listening to the reporter's interview tapes, Hathaway approaches Maddox with a half full cup and takes a swig. In the next shot the mug is nearly full again.
In the early stages of Part One when Hathaway returns with the pork scratchings, the ash tray is empty. From a different camera shot as he lights his cigarette, after opening the packet, you see a cigarette resting in the ash tray.
The date on the Newspaper at the beginning of the show is Thursday 17th October 2001. The 17th was a Wednesday.
When the officers are answering their radio, their radio technique sounds correct, but they neglect to acknowledge the call to attend an incident scene, they just go.
Dr Ward says the bruising just by his left eye was caused by an accident at the gym with a rowing machine. That would have to be just the one item of gym equipment which could not possibly cause such an injury. As an ex-rower Hathaway should have known this.