Guinn 'Big Boy' Williams, who is not in this film but was in Valley of the Giants (1938), from which much footage is used, can be clearly seen fighting in the saloon brawl and with Fallon atop the dam. In the saloon brawl the character "MacIntosh", played by Ralph Dunn, is dressed like Williams to match the footage, and in the fight scene atop the dam Robert Shayne is dressed like Williams, to match the footage from the original film.
Wayne Morris, who is not in this film but was in Valley of the Giants (1938), from which much footage is used, can clearly be seen twice in clips interspersed with shots of Robert Shayne (as Bill) when he is trying to brake the train.