A modern day helicopter cannot fly farther than the length of 3 cities in an entire year.
It takes a modern infantry regiment a year to cross a single city's length.
Riflemen have a bonus against mounted units presumably due to their rifles, yet modern infantry do not.
Archers due to their ranged attacks get the chance to attack their enemies before the enemies get close, yet when they first received guns they decided that this was dishonorable.
Battle fronts do not exist. Instead, modern day armies move around in clumps like stacks that bring doom.
A stealth bomber cannot destroy a wooden boat.
Civilians require food and may starve, but when drafted or volunteer for the army they no longer require food or water, aren't bothered by the weather and live forever.
A bunch of guys with wooden clubs can enter New York City and raze it to the ground, effortlessly defeating the police, civilians (many armed with guns or at least knives), bodyguards, civilians in trucks/cars/other big vehicles, and burn concrete/steel reinforced skyscrapers many of which are designed to withstand earthquakes to the ground.
uhh... that's because a longbow fires accurately up to four times as far as a musket.