I normally take grapes as said above, they really hit the spot while watching a film.
Last time though i opted for strawberries to see Kung Fu Panda, a little boy behind me very loudly said "why is she eating strawberries mum?", i went as red as one i can tell you!!
Those rainbow drops are low in syns and great to take too, it's almost like eating popcorn. Or make your own pick and mix with marshmallows and foam bananas and other low syn sweets even if you only have a tiny amount with your fruit you won't feel like you are missing out then.
Hope you enjoy the film, i wat to go see that but my mates are skint and my boyfriend won't go, tut!! lol