Revealing mistake: When Zod is arrested, his bloody facial wound is a glued-on prosthetic.
Revealing mistake: At the end when the drone crashes in front of the car and the soldier gets out you can see the footprints in the sand from previous takes, in the exact spot where he steps.
Answer: Kryptonians aren't invulnerable. It just takes a lot to hurt one after he has been charged by our yellow sun. There are several beings who are strong enough to break a Kryptonian's bones. Doomsday, Darkseid, etc. Since both are roughly equal in strength on Earth, its no different than one human breaking another's neck.
Grumpy Scot