I remember watching The Hurt Locker (starring Jeremy Renner), the movie is meant to depict the Iraq War in 2004 but for some reason there’s a scene where an iPod Touch (releases in 2007), XBOX 360 (releases in 2005) and Gears of War (releases in 2006) present in the barracks even though these did not exist yet. Another anachronism from this movie is when a American soldier spots an Iraqi recording him ready on uploading the footage via YouTube (the website didn’t exist yet until 2005 when the story is set in 2004).
There was a little movie about the 18th century baroque composer Vivaldi. From my memory (like 20 years ago) it showed him using a modern violin bow. And the music played was from recordings using modern instruments. My area of expertise is early music so it pissed me off.