At about the 5:36 point, Lady Chetwood is getting into her yellow Volvo outside the house. A Land Rover is seen parked at the right of the screen, parallel to the Volvo. The shot changes to a shot of her husband at the door, and now the Land Rover is parked sideways to the left of the front door.
When the book club ladies are discussing the value of their stock holdings, one says it's worth £150,000. When the details are shown on the laptop at least twice, the value is over £1.8 million, with a profit of over £900,000.
While it isn't clear if Troy was simply taking a phone call and returning to Barnaby at the pub table, it appears that he's joining him after finding out that the contractor received a call canceling the victim's appointment. Troy goes to take a sip of his beer and momentarily looks surprised that the pint is already half-finished.
When Dr. Rupert Bradshaw is taking Lord Chetwood's blood pressure using a manual blood pressure cuff, he does not have a stethoscope.
When Ginny Sharpe is killed in the swimming pool blood pours into the water. When her body is discovered there appears to be no blood in the pool. However, in the time between her death and the discovery, the blood would have dispersed so that it is no longer visible. This is not so the amount of blood coming from the wound was far to great for it do disperse completely.
The burnt out car has obvious clean cut pillars, indicating the wreck used for the special effect had a previously severed roof.