Factual error: He has a 55 gallon drum heater in his cabin which was not invented at the time.
Factual error: When John Thornton is in the bar, Hal comes up and punches him in the face. They fight and argue, and Thornton proceeds to say that Hal "sucker punched" him. However, the term sucker punch was first known to be used in 1926 while Call of the Wild was published in 1903. The story itself took place in the 1890s.
Factual error: After running the falls the canoe develops leaks that shoot up above the gunwales of the canoe. Water doesn't work that way, the highest that the water can shoot up is the level of the water in the river. Bernoulli's principle makes things even worse if the water is moving relative to the canoe. (01:05:00)
