Factual error: When Shawn is talking to Belle over the phone, the Eiffel Tower can be seen outside her window, yet, she's supposed to be in Milan, Italy.
The Night of the Wolf - S2-E27
Factual error: Several airplane contrails are visible in the sky as West gallops his horse to Stefan's coronation.
Sucker Bait - S1-E7
Factual error: It is quite true that atoms that do not occur naturally are bad for humans. However, in a space age as this story's, that would apply to most or even all planets. It would be a well known risk that didn't require an abnormal specialist to diagnose. (This fact rarely figures in other SF, because it would severely limit most stories).
Factual error: At the start of this episode you see the terminal at Washington Reagan National Airport, but when Mr. Haslett picks up his ticket you hear an announcement stating it is the Seattle, Washington Airport. (00:00:20)