The Internet Movie DataBase has more information about this movie
When the noble six hundred, lances level and stirrups touching, pace, canter, and, finally, charge down the mile-long valley, with the enemy guns tearing great holes in their ranks, you are a dead stock if your pulses don't thunder and your heart quicken perceptibly. This scene may be villainous history, but it is magnificent cinema, timed, shot, and cut with brilliance. It only cramps the patriotic effect a trifle that the Union Jack, nine times out of ten in the picture, is shown resolutely flying upside down.
Though allegedly “based on the poem by Alfred Lord Tennyson,” this is no more than a travesty of history, most of it taking place in India. As pure entertainment however it is a most superior slice of Hollywood hokum and the film which set the seal on Errol Flynn's superstardom.