Other mistake: Truck chase scene, the driver-side fender changes color. Starts as red then changes to blue. (00:18:27 - 00:20:10)
Continuity mistake: When John is killed, the stool on the right moves away between shots.
Revealing mistake: In Guatemala, when young Terminator shoots John, young Arnie's face is used in the front shot, but in the shots from behind, one can tell it's not Arnie's face but a body double's, Brett Azar's.





Answer: The simplest answer is, this is a movie, and movies often exaggerate, change, or fabricate details that logically could never occur in real-life. This is a perfect example of a deliberately faked action sequence that is contrived solely to entertain the audience by employing a 'suspension of disbelief.' It's more exciting and suspenseful to be able to see the plane crash, even though, as you point out, it realistically would be miles away by that time.
raywest ★