In the scene where the reporter and one of the professors go back to check for damage. The round red object he opens up is a complete (minus 2 machine guns) belly ball turret for a B-17 bomber from World War II. It is minus it's revolving and raising and lowering mechanisms.
Despite being an almost forgotten star these days, Marguerite Chapman was James Cameron's first choice to play the old version of Kate Winslet's 'Rose' character in Titanic (1997). However Chapman was not in good health and had to reluctantly decline so was replaced by another forgotten star of the golden age of Hollywood, Gloria Stuart. Ironically Stuart was eight years older than Chapman but outlived her by eleven years.