I manage an 11 screen theatre, and have looked into owning my own. As a part-time business, I run a concession operation at flea markets and other big events,so I have always been interested in concessions. I have also managed single screens, triples etc,so I understand the space restrictions you may have. Some questions you may want to ask yourself before adding items:
1.What are people asking for?
2. Is your theatre busy enough to add these items and sell enough of them to justify it?
3.Is the item I am considering adding going to take away from a more profitable item?
That being said, I am a firm believer in the old standby's popcorn,soda,candy. There are items that are very popular and require little in the amount of work,or original start up costs.
In no particular order, these are some very profitable items I would suggest,(but you know your own market better than I).
1.Nachos with cheese-You can get a used cheese machine cheap at any restaurant supply store,you can buy chips at a local SAMS or warehouse club. Minimal prep time,and I haven't noticed any of those "mess" problems.
2.Pretzel with cheese-If you sell nachos, you may as well sell pretzels (you already have the cheese).You can buy pretzels locally at a SAMS or warehouse club.SUPER PRETZEL is the brand around here. All you need is a freezer to keep the SUPER PRETZELS in and a pizza oven to bake them. Minimal prep on a nice mark-up item.
3.Cotton Candy- You can buy a cotton candy machine for about $500-$800. Its messy to make (make it in a back room) bag it, and it sells for $2.00-$2.50 cost on item about 25 cents.
4.Sno-Cones/ A great item,If you sell fountain drinks, then you already have the ice. Buy a sno-cone machine for about $500. You only need the cones and the flavor-your cost on this item about a dime and $1.00-$1.50 retail.kids love em.
5.Those are some of my favorite high profit items-some others to take a look at would be pizza (or pizza by the slice) and hot dogs.
6. Some thing I would stay away from (at least in my markets) fresh brewed tea,cappuccino,hot chocolate,muffins,cookies,bulk candy,bottled juices-all have been losers here and lack the high profit we all like.
and finally... If you don't have a Gold Medal catalog, get one,(I wouldn't suggest ordering anything through them $$$-I like used equipment-but their catalog gives you lots of ideas of things to sell.