There are some continuity issues while switching between miniatures and live-action shots. The most noticeable is when Anna arrives at the church ahead of the flood. In live-action there are several horses and buggies parked outside as she runs in, but they're completely gone in the next shot outside of the church, which is a miniature.
The film has railroad tracks crossing right in front of the dam. The dam fails just as the train carrying the villain (in the form of the timber company owner and architect of this disastrous flood) crosses in front of it. Evidently, this was the director's effort to have the villain punished for his wicked deed of putting profit over lives. BUT there was no railroad crossing in front of the dam. And as there was no timber concern there was no evil company owner/villain to punish. YET there was a railroad running much of the valley through which the flood traveled to Johnstown. And this is where one of the greatest heroes of the disaster achieved notoriety. An engineer, John Hess, heard the rumbling of the approaching flood, threw his engine into reverse and raced backwards down the valley, ahead of the flood, blowing his whistle to warn people of the approaching disaster (this warning saved many people who were able to reach high ground and safety). Eventually, the flood waters caught up to the train and knocked off the tracks (and added it to the debris field at the head of the flood). Fortunately, this true hero did survive this ordeal. So, no train tracks in front of the dam, and no villain to punish. BUT a railroad down the valley in front of the flood, and a genuine hero to boot. One must ask why the director felt it necessary to choose a completely fictitious story with a villain, when he could have chosen a TRUE story of heroism.
All correspondence (i.e., telegrams, letters, envelope postmark) refers to the nearby city as "Pittsburg", whereas the intertitle cards correctly spell the city "Pittsburgh". Due to the United States Geographic Board desiring to unify location names ending in "burg", the city actually was spelled "Pittsburg" from 1891 to 1911. However, the flood occurred in 1889, when the original (and current) spelling was in use.
This film is full of historical errors. Biggest of all, the dam was initially created to supply a canal from Johnstown to Pittsburgh. When the Pennsylvania Railroad surpassed the canal, it was sold to the railroad, which in turn sold to wealthy Pittsburgh interests (lead by Frick) who wanted to establish a recreational area around the artificial lake. The dam was then lowered so that it would be wide enough for a road on top. This lowering, of course, would make the dam more easy to top should heavy rainfall ever occur. There was NEVER a logging concern involved with this dam.
Another error is that the dam did NOT fail due to a cloudburst one afternoon. It had been heavily raining over 24 hours (From May 30-31, 1889), when 6- 10 inches fell. Members of the South Fork Club realized that the dam was threatened and tried to remedy the rising water. It continued to rain heavily through the morning and into the early afternoon. Shortly before 3 pm, the dam breached, after more than a day and a half of heavy rain. It did NOT fail after an afternoon downpour.
The film makes a powerful man, the owner of a logging business in quest of a million dollar contract, responsible for the flood, But there was no such conspiracy for profit as there was no logging concern. Instead, it was a conspiracy of the ineptitude well to do Pittsburgh elite who merely wanted an escape from the sticky summers of their hometown. This elite class wanted to be able to get a way from it all, and they wanted it to occur quickly (despite the dangers that this rush presented). Unfortunately, when the dam failed, the only price they paid was the loss of their reputation, while it was the residents of Johnstown who paid for this arrogance with their lives.
When the debris field is floating toward the fire, there is one little boy riding a barrel and holding a chicken. Though this child would have seen people drowned and crushed by floating debris, and though he is approaching a fire and the very real prospect of being burned alive, he is actually smiling, if not laughing. Evidently this child was having quite a fun time playing on the water instead of pretending to be facing death and destruction beyond his limited (by his few years) experience.
On a street scene, a woman is sitting on her porch, holding an infant, while talking to a child. As she gets up and walks away, it is obvious that the infant is actually a prop in the form of a porcelain doll.