Either Q was on the plane, or he was with the advance team in Hanoi talking to POTUS when both tweeted at the same time. I have no opinion one way or the other. Well, it does seem odd that they would post from Vietnam if Q wasn’t there. Another possibility: Another member of the Q team was in Vietnam while another was with the President.
If MI is part of the team, and one of the 3 civilians is someone like Stephen Miller, then that could be what happened.
The “advance team” could easily send a picture to the crew of AF1 especially to notify the pilots of the weather at their destination.
https://people.howstuffworks.com/air-force-one5.htm
In advance of every Air Force One flight, the Air Force crew sends C141 Starlifter cargo carrier planes, toting the president’s motorcade, to the destination. This collection of bulletproof limousines and vans, loaded with weaponry, keeps the president safe on the ground.