Yes, you can Tag Switch and return the troops: FIRST, SAVE YOUR GAME, press the "tilde" key (~) to open the command console, then type in "tag HUN" (don't type the quotation marks). Use the diplomatic option to return expeditionary forces (you'll probably need to click on each and every division on the list to return it), but DO NOT start the clock at any point. Tag Switch back ("tag JAP"), and THEN restart the clock. You MAY need to send the troops back toward German territory, where they SHOULD be handed over upon arrival.
Starting the clock while tag switched to another country will almost inevitably prove the old proverb "Anyone can make a mistake, but making 100,000 of them in under a second takes a computer", since the AI will reassign units in your own country to remote locations all over the map, reorganize your OOB, break your most critical trades, throw a pile of useless garbage into your production queue, and do a myriad of other things that will probably take days of real time to find and straighten out. That's why you save beforehand, so if you DO break something (or allow the AI to do it for you), you can go back to a prior save.
