I was playing a local game with 4 AIs and myself. There was Spain, Thailand, Bulgaria, Romania and myself as Japan. I saved and quit and then I opened the game the next day and all of a sudden I was controlling Spain and was in a different part of the map, so I could use some help.
Heir is some help hopefully it will help this is probably what you did you took the other player and you can click on you and click take it should work.