People and objects aboard International Space Station experience weightlessness.
General McClain is shown wearing 4-star General shoulder patches. 4-star generals were not at that time permitted because that high rank was accorded only George Washington. General Ulysses S. Grant was the commanding general of the Union Army and he was only a Lieutenant General or three star rank.
Jet contrails are visible in some of the Civil War-era landscape shots.
The ISS always has docked at least one Soyuz module for emergency escape purposes. One might expect any astronaut capable enough to be on the ISS alone to know how to use said module, eliminating the need for isolation.