Finish Action: Choose an action that the aircraft will perform at the end of the mission. Available choices are "None", "Go Home" ("RTH" on iOS), "Land", "Back to First Waypoint" ("Back to 1st" on iOS) and "Reverse". When using "Reverse", the only way to end the mission is to switch the RC mode to P (S for Phantom 4), "Reverse" allows you to let the aircraft fly to the last waypoint and then replay the mission in reverse using the joysticks or the cruising speed slider.
Got this from the manual. Hope it helps. You can Google "Litchi user manual" and read online or download the PDF. Tells you everything about it.