Factual error: That is not a crocodile that attacks Sue. It more closely resembles an American alligator - the squat, rounded snout gives it away. Australian crocodiles have a much sharper, more angular snout. There are other tell-tale physical features, most notably the placement of the alligator's teeth when it closes its mouth, but that's the main one.
Corrected entry: When the trio drives out to the location where Mick was attacked, they encounter a water buffalo in the middle of the track. Mick honks the horn and yells to get it to move, then gets out of the truck and hypnotizes the beast. Where does it fall over and go to sleep? Right there in the middle of the track. It strikes me that it would be much more difficult to move a sleeping buffalo than one already on its feet.
Correction: It's much easier to drive around a sleeping buffalo than a conscious one. If he were to drive towards the conscious beast, it may think it's being threatened and defend itself. Obviously, Mick does not want the beast to attack the car. Putting it to sleep and driving around it makes more sense.
There are huge trees on either side of the dirt road. No way is that large truck getting past that buffalo.
There was plenty of room on either side of the buffalo to drive around. The distance from the animal to the "huge" trees on the right is wider than the track seems. And on the left was a small tree that if it couldn't be avoid would could be driven over. The rest was just shrubs and bushes.
Suggested correction: You can tell by the shape of the snout and the ridges above the eyes that, although animatronic, it is meant to be a Marine Crocodile that is native to Australia. It doesn't resemble an American alligator, which doesn't possess those pronounced ridges. Also, freshwater crocodiles can be seen in the boat ride scene where Mick motions for Sue to lean up off the edge of the boat. They have the narrower, angular snout that you referenced.
The placement of the alligator's teeth when it closes its mouth shows that it is more like an alligator than a crocodile. In fact, the animatronic puppet is a bizarre mish-mash of physical characteristics of both crocodiles and alligators.