Dr. Marvin Could Have Obtained Saucermen's Death Ray
After leaving Belmont Laboratory, Major Huglin shoots one of the saucermen. Then he and Dr. Marvin take off the alien's helmet from the bio-environmental suit. The alien body, exposed to Earth's atmosphere and pressure, disentigrates. Dr. Marvin grabs the alien's helmet for scientific study.
However, I believe it would have been better for Dr. Marvin to grab the alien's death ray weaponry, maintained in its hands. Then, not only would the Earth have its own weaponry to utilize, but that of the saucermen too! We would be using their own power against them!
FYI, according to the original script of EVTFS, the alien's bio-suit was to have burned up in the forest fire. However, that scene was never filmed. Or, if it was, never included in the film's final release.