The factual accuracy of the series is often criticised by legal professionals and journalists; many of the decisions taken by Deed are unlikely to happen in a real court. The romanticised vision of the court system created by Newman caused a judge to issue a warning to a jury not to let the series influence their view of trialsreferring to an episode where Deed flouts rules when called up for jury duty. Another episode led to complaints about biased and incorrect information about the MMR vaccine, leading the BBC to ban repeats of it in its original form. All six series have been released on DVD in the UK.

Unlike most portrayals of exorcism and spirit possession in fiction, Apparitions is more religiously accurate and fact-based, incorporating the nature of demonic possession as described by the Church. It also recounts historical events associated with Christianity and other Abrahamic religions, which may have been caused by Heaven or Hell, indicating that the War described in the Bible may not have fully concluded.

The series is written by Joe Ahearne.

The mandate of CI5 was to fight terrorism and similar high-profile crimes. Cowley, a hard ex-MI5 operative, hand-picked each of his men. Bodie is a cynical ex-SAS paratrooper and mercenary whose nature ran to controlled violence, while his partner, Doyle, comes to CI5 from the regular police force, and is more of an open minded liberal. Their relationship is often contentious, but they are the top men in their field, and the ones to whom Cowley always assigned to the toughest cases.