Trump departs DC the morning of the 20th, flies to Florida and attends a goodbye rally.
Moments before noon, Trump stages a fake assassination and fakes death (the shot heard round the world.)
At the same time, troops move in to execute arrests in DC moments before Biden is sworn in.
Several days later, maybe 30, once the military operation is complete, and real election results are revealed, Trump makes a surprise return and is sworn in for his second term.
/end of movie