Continuity mistake: When the butler takes the mother and kittens to be abandoned in the countryside he is on a motorcycle and sidecar combination. During the trip the sidecar changes from one side of the bike to the other and back again. Also, when the sidecar separates from the motorcycle when the dogs are chasing Edgar, the wheel on the sidecar switches sides regularly as well.
Factual error: When Clint Eastwood catches an Indian arrow in his left shoulder, he instructs Shirley MacLaine to prime the arrow shaft with gunpowder, which he then ignites as she forces the shaft all the way through his shoulder. Presumably, the burning gunpowder would cauterize the wound all the way through his body, or that's what the filmmakers asked the audience to believe. In reality, gunpowder is historically well-known for causing gangrene in open wounds. With a shoulder full of gunpowder cinders, Clint Eastwood should have died of gangrene and sepsis by the end of the movie.Charles Austin Miller
Other mistake: Like most Sherlock Holmes films 'The Private Life Of Sherlock Holmes' is set in Victorian England: Queen Victoria even makes an appearance. Holmes and Watson go to Loch Ness in Scotland, where they see the Loch Ness monster. (Spoiler alert) it turns out that the Loch Ness Monster is not a living creature, but an experimental submarine. Like most people who would have seen the film on its release in 1970, they are familiar with the Loch Ness monster (even if they do not necessarily believe in it). But the first documented sightings of the Loch Ness Monster were only made in 1933. Nobody ever thought there might have been a monster in Loch Ness before 1933.Rob Halliday