As Rainbow Dash tried to eat Pinkie Pie, Applejack was squeezed out of Pinkie’s stomach. Then, in her haste, Rainbow Dash, unknowing that Applejack was no longer inside Pinkie, tried to fly off, only to fly straight into Applejack’s mouth which was open, as she was gasping for air. As an automatic reflex, Applejack swallowed.
That’s how I see it. Especially since Applejack says “What in tarnation?!” at the top of the frame.
so this is an Accident?
As Rainbow Dash tried to eat Pinkie Pie, Applejack was squeezed out of Pinkie’s stomach. Then, in her haste, Rainbow Dash, unknowing that Applejack was no longer inside Pinkie, tried to fly off, only to fly straight into Applejack’s mouth which was open, as she was gasping for air. As an automatic reflex, Applejack swallowed.