Anachronism

/əˈnæk.rə.nɪ.zəm/ noun medium

Something or someone placed in the wrong time period, out of step with the present era.

A soldier checking his wristwatch in a movie about ancient Rome would be a glaring anachronism.

Memory Trick

'Ana-' (backward) plus 'chron' (time, as in 'chronology') — an anachronism is something that runs backward out of its proper time.