We have gone several years now, and DD1 is very sensitive. I'm always a bit nervous about it, but so far we haven't had any incidents. We wipe her seat/armrests well, but don't let her use any cupholders. If you buy water they will keep the lid (so the animals don't get hold of them). There were peanuts sold at some concessions, but not in the crowd. This year someone ate peanuts a few rows back without any problems for DD1 (didn't know they were there except we had to walk through the shells afterward).
Check in advance - I think the s'mores on a stick might be okay; we got one once before and I think it was okay for PN, but I forgot to check this time.
Have a great time!