I don't know how in depth of an answer you are looking for here, but here goes mine. Throughout the night your concession attendants should be working -so when you finally tell them to close up, there aren't tons of things that need to be done. Throughout the night: Candy should be restocked, ice filled, soda checked, seed, oil, salt, candy, nachos, pretzels,cups, tubs, bags-All supply items, saleable and non-saleable should be restocked. Counters should be continuously cleaned, floor should be kept clean. Depending on what you use to hold your popcorn this may change. If you pop popcorn in a popper, then move it to a warmer for sales, then you can prepop enough for the last set of shows, then clean the popper. IF you pop popcorn and keep it in the popper for sale, you will have to hold that for a little later.
SO, basically, since you've kept up on the stocking and cleaning all night, all they have to do is clean the popper/warmer when you are closed,clean the soda machine, do a final sweeping and counter wipe off, and their done.
The concession stands that are the worst, are the ones whose employees must constantly be told to do everything, those who wait till the last minute to sweep the floor, or clean the counters, or restock.
If they work AHEAD of the GAME they will be fine. I always tell mine, pretend like every show is going to be busy.Fill napkins, straws, stock, soda, seed, oil, candy, and clean, clean, clean...