The first major flaw in the standard account was that James Mackenzie is said to have driven the stolen sheep from Taiko to the Mackenzie Pass on his own, with one dog and a bullock to carry his pack of food, bedding and other equipment. The legend is that his dog Friday was so clever that Mackenzie was able to drive the flock of sheep without any other assistance.
I have driven a flock of one thousand sheep with one dog. In an enclosed paddock where the sheep know where they were going, it was difficult to keep them together, as some would be keen and move fast while the slower ones would be unwilling to move. Driving a flock through rough country that had never been grazed would be extremely difficult for a man and a dog, no matter how skilled the dog.
On the day that the sheep were stolen, Mackenzie is supposed to have driven them in the night up over the high ridge to the north of Mt Misery and down into Cannington by the Pareora River. Sheep do not like walking straight uphill, or downhill. They prefer to go sideways around the hillside and graze. This hill had not been grazed at that time, so it would be much rougher going than it is now. Getting the sheep over the hill with one dog, would be extremely difficult, especially when he had to lead a pack bullock.
Once Mackenzie got down into Cannington, he would probably have had to cross the Pareora River twice to get up into Mawaro. Opposite the Cannington homestead, the river goes quite close to the cliff, so it is unlikely that he could squeeze his sheep through between the river and the cliff. He would have had to cross the river before he got there, and then cross back again further up.
The river was much deeper then, because most of the flow is now taken by the Timaru water supply intake in the Upper Pareora Gorge. Sheep will cross water, but they do not like it. If you hold them close to the river and get a few leaders across, the others will follow, but this would be difficult task for one man. While he was getting the last few stragglers across, the ones that had gone first would be scattering.
As the journey progressed further, he would have had to cross half a dozen streams and rivers. Finding a place to cross would require some scouting, and getting the sheep across would never be easy for one man.
Mackenzie always claimed that he had been hired by a man called John Mossman. This was discounted by the officials, as Mossman was never found. However, given the difficulty of the terrain, Mackenzie almost certainly had assistance. Driving a flock of a thousand sheep over that country would have been almost impossible for one man. He very likely had help, or was helping someone else, perhaps the instigator of the theft.
The standard account suggests that Mackenzie planned to drive the sheep down through the Lindis Pass to Southland and sell them. This is an even more implausible suggestion, as crossing the much larger Waitakai River which would have been even more difficult for one man and a dog.