Haunted Technology — Wraiths can have mechanical or electronic objects as Anchors, which will exhibit weird behavior even when the Wraith isn't physically present.
There are also some races present which exhibit great longevity, such as the Númenóreans, who are longer-lived than other Men, and the Yngvi (elves) native to Caranom, whose age cap is at about a thousand years but age very slowly.
At some point during each episode, host Graham Greene would present what he called "Exhibit A", the piece of evidence that typically broke the case for the police.