Actor Stuart Randall, playing Standing Bear, had all his lines re-dubbed with another actor's voice after filming was completed. Apparently the producers finally realized that most Canadian Indians do not, like Randall, have a distinct Texas accent.
It is stated in the beginning that Duncan MacDonald speaks Cree, but then his adopted Indian son has a conversation with the captive white woman and they both understand one another! He didn't speak English and she didn't speak Cree.