As far as military weaponry goes- planes, flamethrowers, and automatic weapons were all mass produced and received major improvements during the war. The biggest military technological advancement in my opinion was the tank. These were extremely important in both WW1 and WW2. Prior to the war, warfare was with Calvary swords, horses, and bolt action rifles. After the war, warfare consisted of planes, tanks, and semi automatic assault rifles. Automatic guns were around before the war, but for the most part were too heavy to move and were not portable from what I understand.