This was a great 1950's sci-fi film and I always enjoy watching it after many repeat viewings!
I did notice one goof which didn't hurt my enjoyment but nevertheless it was there: When the army started attacking the alien crafts, the shells and bombs couldn't get through due to a protective coverings which shielded the saucers.
When the aliens began firing back with heat rays and explosive bombs while the army was still attacking........how could they? There protective covering was still on and yet their weapons got through. You can't have it both ways: If your protected from shells with an impregnable defense then your own weapons could not fire back while this covering was still on!
I only saw rays, two kinds, red and green, were they not? There might have been some kind of pulsating or phasing to allow their rays through going out, but we wouldn't have the phasing ability to get through. It's something like 3D movies today, as a way of sequentially allowing one eye to see, then the other, too fast to detect.
Speaking of two different rays, I remember Forrester's explanation of the skeleton beam to General Mann: "It neutralizes mesons somehow. They're the atomic glue holding matter together. Cut across their magnetic lines of force, and matter will simply cease to exist." I finally found out what mesons are:
I was reading about mesons on wipkidea and my head started hurting! LOL
I had the same reaction when someone was explaining to me the method of counting cards (in a casino, counting cards is a method of keeping track of the high cards thus improving your chances of winning in blackjack- Not illegal but frowned upon casino personal)
I get the idea, I think? In other words they could fire their heat rays through the protective shields without harming their machines? I think.