Don't know about the chaff and flares, but many aircraft at this time did have the capability to dumb excess fuel in an emergency. Probably not all of them, but many, especially late war aircraft, did. This would be kind of a cool feature, but people would probably abuse it by taking full loads, dumping constantly when they hit combat and then running home. Also would fake a hit, which could be bad in the game.
Would be cool to see though, at least in SEA.