
If the hunters hadn't panicked, would they have been able to fight off the T Rex attack?
They'd still be caught off guard, but we see at least a few of them retaining their firearms and actually shoot at the Doe to apparently no effect. Not a firearm expert so I have no idea what rifles they're depicted having or if those were enough to seriously harm/kill a rex.
Roland would still not have his elephant hunting rifle ammo (or whatever it was) since Nick stole it.
For a what-if scenario 2, you can also imagine Roland wouldn't have access to the tranquilizers either.