Anachronism

And yet here's another cool word. Anachronism is a thing that appears in normal space but its qualities make its presence impossible.

For example, if you went back to the signing of the Declaration of Independence and Thomas Jefferson was holding a Rubix Cube or John Hancock made reference to a Friends episode. The thing is there, but it should not be there eithe because of time or because it is impossible - like a man holding fire in his hand.

It is a common quality of video games.

Read more: http://en.wikipedia.org/wiki/Anachronism