Gunga Din was shot, on location, in Lone Pine California. I have one of the cap badges from the film (a crude lead casting) and on the roundel is the number "77"; a totally fictitious Indian Army Lancer regiment. The cavalry was provided by "The Hollywood Posse", a collection of "Gower Gulch" cowboys, a mounted drill team from Glendale, California (now known as the Saddle & Sirloin Club), and local horsemen recruited in Lone Pine. Back in the late '30s a lot of men could ride, and it was never an issue conjuring up a regiment of cavalry for the movies.

I can't recall who played the Halvidar-- or if he was even credited. It is as likely he was a pukka Indian as a Mexican charro with spirit gum chin whiskers. I'd like to think that, like Victor McLaglen, he was the genuine article.