Hynek gives his son a reflector telescope to view Mars with. Hynek sets it up the wrong way about. On a reflector, the eyepiece is at the top of the tube, not the bottom end. The boy would only see a blurred image of the ground, as the end of the telescope which receives light is pointed down, not up! You can see when the end pointed at the sky is flat and looks metallic. It is - as it is the mount for the mirror. This error could have been avoided so easily. Just look in any telescope shop.
The term "went missing" is used when that term did not gain popularity until more than sixty years after 1952. Back then they would have used the correct term, "disappeared."
When the KGB spy (Currie Graham) went into Dr. Hynek's home office, there was a yellow rotary phone, which wasn't available till later in the 50's when color was mass produced. It also looked too lightweight.