Ah yes, the old days of the 50s and early 60s, where asians were apparently not capable of playing themselves ... but ridiculous, overacting white people were. I remember seeing this kind of thing for the first time with Mickey Rooney in some movie (popular movie, can't remember the title as this is all before my time). I initially thought it was funny, because I was a teen and didn't know any better. However, as time went on, I saw how absurd this kind of casting was - it was essentially putting on 'blackface', but instead with jet black hair and a stereotyped accent a 10 yr old could do (though probably better!).
Fortunately, Wagon Train rises above some of the other negative stereotypes and portrays 'orientals' (I believe thats how they were referred to back then) in a generally good light. WT always has a way of getting a moral message through without sounding preachy and they get the job done here as well. But thats about the only thing that saves this episode from being a rare dud for them