Continuity mistake: In the opening scene, Gwen has a long, loose strand of hair hanging over her left temple - but every time the camera angle changes, it disappears. (00:01:00)
Continuity mistake: When she sees the little boy's ghost, Gwen's hair alternates repeatedly between neatly-combed and windblown/messy, depending on the shot. (00:03:30)
Revealing mistake: From the first "front on" view of Gwen and Owen in the arcade as they are running to catch the alien device, you can see behind Gwen to the right that Owen is being played by a stunt double.
Cyberwoman - S1-E4
Character mistake: In this episode Jack tells Gwen that he does not sleep, yet the next episode, Small Worlds, begins with Jack asleep and dreaming of the day his comrades died on a train, with rose petals in their mouths.
Countrycide - S1-E6
Continuity mistake: In the pre credits sequence, when the lady gets out of her car the antagonist slashes her rear tyre however after the antagonist is attacking her inside the car we see a rear shot of the vehicle, and the tyre is fully inflated.
Continuity mistake: While she's talking to Mary in the flat, Toshiko's hair keeps changing between shots, going from combed evenly to split apart with one section hanging in the middle of her forehead and the rest brushed back. (00:31:30)
They Keep Killing Suzie - S1-E8
Visible crew/equipment: When Owen responds to Susie talking through the computer monitor and says "you frighten the s**t out of me" a boom mic drops into shot above his head.
Out Of Time - S1-E10
Continuity mistake: John is about to eat liver and potato with Emma before she storms out saying, "I don't like liver". While they are talking, the potato is facing Emma and Gwen. After Emma leaves, the liver faces Gwen and the spot where Emma was.
Factual error: Between getting disconnected by the bad guy and calling Ianto, Jack gets a dial tone on the dead man's cell phone. Cell phones don't generate dial tones. (00:11:10)
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)
Captain Jack Harkness - S1-E12
Factual error: "Captain" Jack Harkness actually wears the rank insignia of a group captain, equivalent to an army colonel and never abbreviated to "captain". In fact, the RAF does not have a rank of captain (the equivalent rank is flight lieutenant). Neither does it have the position of "squadron captain", as he is described - a squadron commander in World War II usually held the rank of squadron leader (equivalent to an army major).
Suggested correction: "Captain" Jack Harkness actually wears the rank insignia of a group captain, equivalent to an army Brigadier. The equivalent rank of Captain in the RAF is Flying Officer.
Nope. Group Captain = Colonel (Air Commodore = Brigadier). Flight Lieutenant = Captain (Flying Officer = Lieutenant).
Group Captain in the RAF does in fact equate to Captain in the Royal Navy. The Army equivalent being, as stated, Colonel.
End Of Days - S1-E13
Visible crew/equipment: After Lisa appears to Ianto in the holding area, she disappears, when the camera changes angles you can still see her standing in the corner of the room on the right side of the screen. (00:12:50)