Clouds appear and disappear from shot to shot. For example, during the discussion scene on the railroad tracks about 27 minutes into the film, the clouds above the mountains at the tracks' vanishing point appear in wide shots and disappear in tight shots.
The locomotive seen at the end of the film is a Southern Pacific F7, road number 6396. Even though the film is set shortly after World War II, the F7 did not enter production until 1949 and #6396 would have been produced even later (production ended in 1953, the year this movie was filmed.) Additionally, the F7 was produced as a freight hauler. Southern Pacific usually used the E-series diesel-electric locomotives for passenger trains.
At the climax of the film, Macreedy is attempting to use his tie as the 'fuse' for a fire-bomb. Though his 'dead' arm remains stuffed in his jacket pocket, he clearly uses its hand when tearing the tie.
In the opening train sequence, two different trains were filmed. The first had different locomotives than the second (as evidenced by loco numbers); the second train shown stopping in town had a dining car just behind the locomotives which the first train didn't.
At the end of the movie, Tracy arrives at the station and sets down his suitcase. When the train pulls into the station, long shot shows he is holding it again, next close up, it is again on the ground.
McCreedy rents the U.S. Army quarter-ton truck (jeep) and drives it around with his one arm. That model truck only had a standard transmission. Yet you can hear the gears shift but McCreedy never engages the clutch or works the shifter.
As the train approaches the town, the horn blows twice, which is the signal for starting up. The mandatory signal for a grade crossing (long, long, short, long) is never blown, although one clearly exists. When the train departs, the conductor makes a confused hand signal to the engineer resembling the horizontal motion that means "stop" rather than the vertical motion that means "go". The engineer never responds with the "long, long" starting signal.