Shots of the X-80 use footage of a Convair F-102 Delta Dagger, but not always the *same* F-102, as evidenced by the identification number on the side of the aircraft. During re-entry, some footage of a Convair F-106 Delta Dart is used as well, giving the impression that the plane changed from an F-102 to an F-106 and then back again.
When Col. Martin orders the Sergeant to post a guard outside the operating room, the Sergeant salutes. The Colonel is "covered" (wearing a hat); the Sergeant is not. Military protocol specifies hats are not worn indoors and salutes are not rendered indoors nor when "uncovered."
As the X-80 is gaining altitude, there is a shot of the plane supposedly in a steep climb. But the clouds in the background are obviously at the same sharp angle, revealing that the footage of a level flight has just been "tilted" optically.