The reason they come back right after delivering the food is so they can make sure your meal is as you ordered. Is something cold or taste especially bad? Was the wrong sauce or filling used by the cook?
If I have a problem with the food, I'll get a waiters attention - perhaps with a snap of my fingers - which is expected and not at all rude and let the waiter know.
Snapping my fingers at the waiter isn't something I'd ever do in the US though.
I expect writing to have minor flaws.
I expect a sandwich to be a sandwich.
Mistakes that aren't noticed by the time all the food is handed out should be rare, and there's no problem in flagging someone down in that case.