An anachronism is something that doesn't fit its time period, like if you say you'll "dial" your smartphone.
Anachronism comes from the Greek roots ana- which means "against" and chron- which means "time." Together they represent a situation in which something happens that should not because it belongs to another time period. You see anachronisms all the time in the movies — they occur when you see a jet fly over a Civil War battle! Or knights jousting over a maiden during the time of Shakespeare!