The Doc calls out the name of the next patient, Alice Cooper.
Rory Wilton plays Chippy Miller in this episode and a further six. He earlier played the part of Mr Hubble in episode 5.1, Preserve the Romance (2011).
PC Penhale forgot to charge his Taser. The type of stun device that looks like a gun and shoots out little darts trailing wires does not get recharged. The front half of the gun is a replacable cartridge which contains the dart and wire, the propellent that shoots out the darts, and a serious battery to deliver multiple shocks. Each cartridge is used once then replaced. Cartridges cost over $35. a pop.
When Mrs Winton brings out a rifle and shoots a hole above Doc Martin's head, he could simply have grabbed the gun as it is clearly a bolt action rifle, requiring the bolt to be drawn back in order to reload. Sights on the rifle would also suggest (but not confirm) that the rifle was not automatic.