There is a continuity error between the second episode of the video game "Blood of the Cybermen" and the television episode "The Pandorica Opens". On both occasions, Amy Pond doesn't recognise the Cybermen, even though the latter is set chronologically after, albeit the video game was published later. Amy also encountered them in the two video games "Doctor Who: Return to Earth" and "Doctor Who: The Mazes of Time", both also released after "The Pandorica Opens" but set prior. It's assumed by fans that this could be due to the cracks in time altering Amy's memories.