Will states that the last reported serious outbreak of bubonic plague was in Scotland in 800 AD. While the definition of a "serious" outbreak might vary, it would certainly include the 14th century outbreak - also known as the Black Death - which killed over 50 million people across China, the Middle East and eventually Europe, and the 17th century outbreak in Britain which ended around the time of the Great Fire of London.
When Ashley phones Helen towards the end of the episode, she is using an iPod Touch rather than a phone.
When the Kabbalis Nocturnum soldiers search the area surrounding the crypt, one reports finding "45 mil" casings on the ground. He should have called them "45 cal" as .45 ACP is measured in inches. Additionally, there is no pistol cartridge that is 45 millimeters (which would work out to over 1.75 inches in diameter).