Miracle Day: The Blood Line - S4-E10
Continuity mistake: At the very end of the episode, when Rex is checking his phone, when the camera is facing him, his phone is being held in portrait, but when the camera is over his shoulder, looking at the screen, the phone is in landscape. This is shown twice, when the camera shots switch. (00:53:35)
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