Historically each White House seems to get its own IG account - trump and Obama whitehouse accounts are separate.
This picture could have been taken in the climate controlled botanical gardens - although unlikely - the walk doesn’t seem to match the botanical gardens.
Possible explanation of the Arlington 21 Gun Salute having 3 cannons instead of 4 - Arlington’s primary mission is state funerals, where 3 cannons are customary. The video we keep linking to is at Arlington, whereas Trump’s salute looked like it was setup on Capitol Hill. The timing of the salute is still weird, but Army regs do indicate the timing is dependent on ammo quality and team capability.
Keep the hoopium flowing