"DVD Talk" said of this film that it " . . . has a lot in common with John Ford's Stagecoach (1939) in that it's essentially a tale of a motley mix of Anglos confined in a train car, racing across an Indian plain trying to evade 'bloodthirsty savages'. It may be a blatant reworking of Stagecoach (1939), as the original story was co-written by John Ford's son Patrick Ford and Maureen O'Hara's husband Will Price. The final screenplay was adapted from a script by screenwriter Frank S. Nugent, the writer of 11 Ford films."
The famous viaduct sequence in the movie was shot at Anchurón Bridge which is situated in Fonelas, Andalucía, Spain.
The old railway seen in this picture is now abandoned and no longer used. The railroad originally traversed the northern part of the Sierra Nevadas, the mountain range in the region of the Spanish provinces of both Granada and Almería.
This picture's setting, the North-West Frontier Province of colonial British India in 1905, is now in modern-day Pakistan.
J. Lee Thompson's tight direction of this film drew him to Carl Foreman's attention after he fired Alexander Mackendrick from The Guns of Navarone (1961) and needed a director quickly. After original director Alexander Mackendrick was fired, star Gregory Peck saw North West Frontier (1959) and agreed for J. Lee Thompson to take over.