We packed a separate bag with a couple of books, cuddly toy, crayons, paper, baby wipes, playing cards, tissues - if i think if anything else I'll let you know.
In my own bag, I kept a couple more "contingency" toys, like finger puppets in case all else fails. Try and pre-book an emergency exit or ailse seat and book sit one on either side of the child.
Don't let them take everything out of the bag at once and have set times for playing, resting and eating. No other toys until they put the other ones away. HTH