Despite the assaults, the gunshots, the train's wagon never shows damages outside or inside, afterwards.
During one of the last scenes, the one with Van Leyden and the Gatling gun, the car's front door is damaged. The scene immediately after shows the same door intact.
When Capt. Scott is rescuing the young prince there is a attack on the city of Haserbad with men in foot and horseback and the British are shelling the attackers. Then when the Scott party arrives it all goes quiet during their discussions. Then the attack appears to start anew with the attackers well away from the city walls again.
In the opening narration voiced by actor Kenneth More (playing Captain Scott), we're told the young prince is six years old, but later, at the Governor's palace, Sir John says that the boy is five.
Just before the old train departs, Capt. Scott is leaving the compartment, but sticks his head around the door to give safety instructions. After the cut, the long shot shows him exiting the compartment again.
Early steam engines without a water tender could only travel 10-15 miles between water stops.
Incorrectly regarded as a goof: The Empress of India is a tank engine which has water tanks on both sides of the boiler. Tank engines do not require tenders.
After Gupta is shot he is laying on the coal tender and Lady Wyndham sends a parasol with Scott to keep Gupta's wounds out of the sun. During the next scene Gupta holds the parasol and the shade is clearly well ahead of him on the back of the engine. At no point does he hold it to shade himself.
As Captain Scott and Van Leyden talk beside the trainload of massacred refugees, one of the dead men, wearing a yellow turban and hanging out a train window behind Van Leyden, visibly raises his head, turns his face away in the opposite direction, then resettles his head in a more comfortable position, all the while Scott and Van Leyden are talking.
(at around 1h 24 mins) During the conversation on the train, the background scenery is moving giving the impression the train is going backward, i.e. the engine was pushing the carriage from the back. In other scenes it was shown the engine was pulling the train from the front.
At the end of the movie the captain is wearing a wristwatch in 1905.
On wristwatch's in 1905, the wrist watch had been around since around 1810, mainly worn by women, men usually wore a pocket watch, but it was British military officers that started to use wristwatches in Burma (1895), Sudan (1898) and the Boer war (1899) so they had been in wide military use for up to 20 years before the movie's story takes place.
Most of the rifles carried by both the British/Indians, and the rebels, are the Lee-Enfield SMLE, which was only just being introduced at the time and so unlikely to be in such wide use. However, when Capt Scott cleans one with a pull-through on the train (just after handing one to Peters), with the bolt removed a bridge charger guide is visible, which identifies it as a Mark III, introduced in 1907. There are also a couple of No. 4 rifles visible used by rebels, much later versions (late 1930s) of the Enfield.
The British breech loading cannon with a retracting barrel appears to be a Vickers QF 2.95-inch Mountain Gun. According to another source, these were used in Africa but never employed in India.
In the scene where the passengers cross the damaged railway bridge on foot, before the locomotive gingerly follows them, there are some very mid twentieth century electricity pylons visible in the distance in some of the wide shots. Electricity pylons didn't come into use until the first ones were built in Scotland in the late 1920s. India didn't have any until at least the 1950s and maybe later.
The movie takes place in India in the early 20th century, but 1950s British trains can be seen in the background through the locomotive cab windows at various times. (Some cab-interior shots were done on a studio set with stock background footage.)
In one shot near the end of the film, whilst the insurgents are attacking the train, the shadow of the camera helicopter is clearly visible on the ground.
In the attack on Haserbad the attackers are shown running towards the city's walls. None of them are carrying ladders or poles and yet the walls are breached with large ladders.
When the train is stopped by a section of damaged track Scott has the train pull out of the tunnel where it could be hidden. The logical thing would have been to leave the train in the tunnel, remove some track from behind the train out of sight in the tunnel and then repair the track ahead without exposing the train.
When the train stops to get water at Shamshara Scot gets the pump running to draw water. The passengers need to carry the water to the train which they do not bother to back up closer to the water. The passengers carry the water an extra thirty or forty feet to the train engine than necessary.
When crossing the blown up rail trestle the passengers don't bother creating a rope out of clothing or other materials to make it safer to walk across the gap. It's very unlikely that nine people would all be capable of walking across that high gap on a three inch rail unaided.