No living creature could possibly survive arcing current from high-voltage power lines like when Ryu uses one as a zip line.
The drones that attack Ryu have but 1 rotor. It is impossible for any drone to fly with anything less than 2 rotors.
The airship explodes into flame after Ryu defeats the boss. Unless it has hydrogen gas, an airship should not burst into flame - and ever since the Hindenburg disaster as well as the downing of Zeppelins during the Great War, hydrogen was deemed an unsafe gas to use in airships.
Certain arrows can be obtained which say 'APFSDS'. 'APFSDS' stands for 'Armor Piercing Fin-Stabilized Discarding Sabot', which is a projectile used for tanks. The central dart of this round is made of depleted uranium and is far too heavy to be propelled by a bow.
North American birdsong can be heard in the background of the ninja fortress.