Factual error: Steve McQueen remarks that the chunk of meteorite is hot - though this is a common misconception (and probably belongs on several movies' boards), meteorites are almost invariably cold, given that by the time they hit Earth their frigid inner layers are exposed by the friction of air drag. (00:20:40)
Factual error: When Van Helsing gives Tania his coat he tells her she looks like a teddy bear. The first teddy bear was made in 1902, 17 years after the movie takes place.
Factual error: Tarantulas do not spin webs.
Factual error: This horror-fantasy film (a 1958 knockoff "The Mummy") was inspired by the faceless whole-body plaster casts taken from the volcanic ash of Pompeii, at the foot of Mt. Vesuvius. The running mistake in this movie is the assumption that the faceless bodies of Pompeii were 2000-year-old mummies preserved by volcanic ash and could, thus, be re-animated (by radiation, in this case). The fact is, the victims at Pompeii were originally encased in hot volcanic pumice and ash, and the corpses then disintegrated, leaving hollow "molds" of human bodies underground. It wasn't until the mid-19th Century that archaeologists first discovered the molds, filled them with plaster, then extracted the whole-body plaster casts for display. Since the faceless bodies of Pompeii are nothing but modern plaster casts, there would be nothing to re-animate, by radiation or any other improbable means.
Factual error: The film begins in 1860, but the majority takes place 20 years later, so 1880. When James Rankin obtains files on the Haymarket Strangler/Edward Styles case we are shown another box labelled with details about Jack the Ripper, who wasn't active until 1888.