Food safety
Can dogs eat popcorn?
Yes, but be careful
Plain, air-popped and unsalted is fine as an occasional snack. Butter, salt and sweet coatings aren't. Unpopped kernels can break teeth.
Being honest about this
Dogs differ, and amount matters — a crumb of something rich is not the same as half a packet. Treats of any kind should stay under a tenth of what your dog eats in a day. If you're unsure, your vet would far rather take the call.