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.
Torchwood (2006)
1 revealing mistake in Ghost Machine
Starring: John Barrowman, Eve Myles, Gareth David-Lloyd, Kai Owen
Children of Earth: Day One - S3-E1
Revealing mistake: When the children are possessed by the 456, they're supposed to be frozen and stare blankly ahead. But during the second possession, as the camera is panning across a school playground, a boy on the far right is looking directly at it. As it moves closer to him, he swivels his eyes back to where they're supposed to be. (00:16:30)
Captain Jack Harkness: Captain Jack Harkness, note the stripes.
Captain John Hart: Captain John Hart, note the sarcasm.
Captain Jack Harkness: Hey, I worked my way up through the ranks.
Captain John Hart: I bet the ranks were very grateful.
Trivia: Torchwood is an anagram for Doctor Who, the show of which this series is a spin-off.
Question: How did Jack get the Doctor's severed hand?
Answer: He might have requisitioned or stolen it from Torchwood London, or he might have been ready down below once it'd been severed, searching for "the right Doctor" and not knowing that the newly-regenerated Doctor was the one he was looking for.
Captain Defenestrator