Factual error: When Cindy wanted a hitman to kill Ian she looks in the yellow pages to find one. Surely the police and the makers of the yellow pages would have been alerted if a hitman agency wants to advertise itself in the yellow pages?
Factual error: A 250-year-old sea chest recovered from the ocean floor is opened, and all its paper items are perfectly dry: the log book can be opened and read, and the letters can easily be unrolled. Highly unlikely. The chest's wood and pitch would deteriorate (salt water is extremely corrosive), and the paper should be damp and crumbly, at the very least. Even more likely, it would have become a lump of unreadable sludge.
Factual error: At the beginning of the episode, Dorothy tries to turn off the dirty video that Sophia rented. She presses the fast-forward button on the VCR remote by mistake, and the music on the television continues at a faster pace. However, most if not all VHS players (in the 1980s and today) do not play audio whilst fast-forwarding or rewinding.
Factual error: 2-7 "The Crimsom Avenger": At Dunwyn Erwyllan grabs a bundle of money bills from a fishmonger. It may be just a curiosity since paper money wasn't used in real medevial times, but it is still odd as gold coins are still in heavy use in all other episodes. Even the royal treasury, which is robbed in this very episode, has only bags of coins and no bundles of paper money.
The Murder's in the Mail - S1-E6
Factual error: Dead blonde guy is sitting upright in the chair, as Dave/Maddie close in, and Maddie realises he isn't moving. David goes to him and smacks him across the shoulder, to "wake him up" and blonde dead guy, right on cue, instantly slumps over a table at his right side, when the direction that David hit his shoulder, should have sent the dead guy slumping more forward, then at the front edge of the table. Obviously staged for the actor's comfort.
Song of the Younger World - S2-E20
Factual error: The 19th Century reformatory has modern electric light bulbs hanging from the corridor ceilings. (00:21:10)