Some people can’t get their heads around the seeming appearance of a single contrail. Somebody correct me if I’m wrong, but this particular aircraft has three engines which are grouped relatively close to the body, so their separate contrails might appear as one, especially from 35,000 feet. That’s another thing. Some people here are perplexed at the absence of more contrails in the sky over LAX. We have to remember, this flight was overflying LAX on it’s way to PHX, at approx. 35,000 feet....cold as hell....conducive for big time steam making if you will. Practically all other commercial aircraft were coming in or out of various LA airports....low level...warm temps.....little contrail making opportunities.
With the naked eye, perhaps, especially in hazy skies. With binoculars, nope, no mistaking one for the other at that altitude. Airborne with a high-quality camera equipped with zoon lenses, I don't know from personal experience, but ... I'd be kinda surprised if it was easier to misidentify a commercial contrail for missile plume.