Character mistake: When Grandad collapses, the Doc calls Morwenna's grandfather Mr. Dunwich, which is the surname of one of his patients in this episode. The grandfather has the same surname as Morwenna, which is Newcross.
On The Edge - S2-E9
Continuity mistake: When Al goes to the ship to get the explosive, his dingy is powered by a Seagull outboard. When he returns, its a Mariner.
Don't Let Go - S5-E6
Character mistake: Mr. Coley the janitor climbs up on the roof and Doc Martin follows, but on the roof he keeps calling the janitor Mr. Munston.
Aromatherapy - S2-E4
Visible crew/equipment: PC Mark pulls over Caroline. When the car door opens the camera crew is briefly seen in the black car door pillar reflection. (00:28:30)
Character mistake: Dr Ellingham makes two character mistakes in short succession in this episode. First, in the bedroom scene with all in attendance, he calls Mrs Dunwich 'Mrs Winchelcy'. Then, when attending to Morwenna's Grandfather William in his garden he calls him "Mr Dunwich." Apparently his character name is William Winchelcy and not William Norcross (Morwenna's surname).