What is the word that describes a word or phrase that appears in a book or movie that doesn't belong because it's too modern? All I can think of is anomaly. Any ideas out there?
Anachronism.
Though there are no words that make the distinction between too old and too new.
It's true that there's no distinction, but in practice the distinction isn't needed. Nearly all major misplacements are in the 'too modern' direction.
Could be some localized exceptions in novels or stories set during the period of great inventions, say 1860-1960. For instance, many cities had telephone and electric service long before they had indoor plumbing. A writer could reasonably assume that an outhouse would imply a completely 'primitive' place, but in those cities he'd be wrong. It was common to see a TV antenna and an outhouse on the same home.
A lot more the other way, present tense, same as "dated" :
Our education system is anachronistic.