Factual error: In Season 2, Episode 3, Peter and the Irish family rob the bookmakers and the security guards shoot at them. In Ireland, even the police don't carry weapons. Let alone security guards.
Captain Jack Harkness - S1-E12
Factual error: When Gwen finds Toshiko's hidden message from 1941, she realizes that it was written in blood, and her flashlight reveals the bright red letters on the now-yellowed piece of paper. But after 60+ years, the iron in the blood would oxidize. The writing on the note should be rust-brown, not red. (00:33:40)
Factual error: When the girls input the thing they call an IP address, it is not an IP address. The numbers are out of range (0-255). This isn't like a "movie" phone number - the address they use is fundamentally impossible. (00:06:05)
Factual error: In the episode where Kyle, Lori, and Josh first go to the pool together, Kyle jumps off the diving board, but he's only in the water for about three seconds before he sees Amanda, who is already swimming toward him. This means that he was in the water for just a second or two before she jumped in. That isn't enough time for anyone to appear to be drowning, especially to a trained lifeguard like Amanda.
Suggested correction: First, at least 10 seconds pass before Amanda jumps in, not 1-3 seconds. But that doesn't mean only 10 seconds passed in the show. But additionally, Amanda already knows Kyle has memory loss and could be thinking Kyle forgot how to swim or forgot that he can't swim. So she goes to get him.
Factual error: At the dance in 1947, a US flag with 50 stars is visible.