What is the word for the mistake of placing an event or object in the wrong age or decade, such as a film star in a movie about Roman times wearing a robe made of nylon?
The word is anachronism:
anachronism The representation of someone as existing or something as happening in other than chronological, proper, or historical order.
To use it as an adjective or adverb, use anachronistic or anachronistically.
I think you might mean anachronism. (sp?) I have too much cold medicine pumping through my bloodstream to know if I spelled it correctly.