Fun!! Are you sitting in your car or getting out? If I'm sitting in the truck bed/in camp chairs, I'd do sushi, fruit, wine. If I'm sitting in the car, probably sub sandwiches with chips and fruit.
I love sushi but I'm not sure I'd do it at a drive-in; part of the enjoyment for me is the visual, and I imagine I wouldn't really be paying attention to looking at the food during the movie. I'm also not that great with chopsticks so I'd probably lose half of it down my top.
The only problem with crackers is I'd have crumbs all over the place. Maybe I'm just a messy eater...?
I'd probably opt for something like burgers and fries. Sitting watching a movie while eating fries out of the bag would be nice...
I would eat before and just bring movie type snacks. It starts really late doesn't it? Eating in the car in the dark sounds potentially challenging. Especially something like sushi where I would end up dropping soy sauce everywhere.