Well he is fighting a cg character, whether or not someone was standing in for goro or he had to fight thin air is anyone's guess. I'd presume someone was there in a greenscreen outfit, can't be easy to choreograph a fight against an 8 foot 4 armed opponent as there's really no frame of reference as to how that would go in practical terms vs a game fight where physics don't apply.
The Jax fight was absolute garbage aswell. It really wasn't the best.
The story is tripe but then you don't watch Mortal Kombat for that lol.